AGRICULTURAL WATERSHEDS OVERVIEW DATA ANALYSIS AND EXTRAPOLATION

F I N A L KEPORT - PROJECT IB AGRICULTURAL WATERSHED S T U D I E S

INTERNATIONAL REFERENCE GROUP ON

INTERNATXONAL J O I N T COMMISSION

TASK GROUP c (CANADIAN SECTION) ACTIVITY 1,

GREAT LAKES POLLU'CION FROM LAND USE A C T I V I T I E S ,

D.R. C o o t e Land Resource R e s e a r c h I n s t i t u t e

R. D e H a a n Engineering and S t a t i s t i c a l Research Service

AGRICULTURE CANADA O t t a w a

In C o o p e r a t i o n With O n t a r i o M i n i s t r y of A g r i c u l t u r e and Food

O n t a r i o M i n i s t r y of t h e E n v i r o n m e n t

D e c e m b e r 1978

DISCLAIMER

The study discussed in this document was carried out as part of the efforts of the International Reference Group on Great Lakes Pollution from Land Use Activities, an organization of the International Joint Commission, established under the Canada-U.S. Great Lakes Water Quality Agreement of 1972. Research Branch, with data-gathering support being provided through cooperative projects with the Ontario Ministry of Agriculture and Food, and the Ontario Ministry of the Environment.

Funding was provided through Agriculture Canada's

Findings and conclusions are those of the authors, and do not necessarily reflect the views of the Reference Group or its recommendations to the International Joint Commission.

TABLE OF CONTENTS

DISCLAIMER TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES ACKNOWLEDGEMENTS

1 SUMMARY AND CONCLUSIONS

2 INTRODUCTION

3 METHODS AND PROCEDURES

4 RESULTS 4 . 1 Preliminary Analyses

4.1.1 Validity of NAQUADAT Loadings 4.1.2 Seasonal Variation

4.2 Correlation and Regression Analysis

4.2 .1 Correlations Among Watershed Characteristics

Page

i ii iii iv V

1

2

4

9 9

9 9

10

10 4.2 .2

4.2.3

Correlations Among Water Quality Parameter Loads and Flow Weighted Mean Concentrations 1 3 Relationships Among Water Quality Parameters and Watershed Characteristics 1 3

4.2.3.1 Simple Linear Correlation 13 4.2.3.2 Multiple Linear Regression Analysis 16 4.2.3.3 Non-Linear Regression 25

5 EXTRAPOLATION OF RESULTS 29 5.1 Constraints To Extrapolation 29 5.2 Extrapolation To The Canadian Great Lakes Basin 29

6 REMEDIAL MEASURES IMPLICATIONS 4 1

REFERENCES 42

APPENDICES A Watershed Locations, Characteristics and Water Quality

B Correlation Coefficient Matrix 58 C Extrapolation of Agricultural Loading to the Entire

Great Lakes Basin 65

Data 44

ii

LIST OF TABLES Page

Number T i t l e

Se l ec t ed Resu l t s of Regression of Suspended S o l i d s and T o t a l Phosphorus Unit-Area Loads and Flow-Weighted Mean Concentra- t i o n s

Se lec t ed Resu l t s of Regression of Ortho-Phosphorus Unit-Area Loads and Flow-Weighted Mean Concent ra t ions

Se lec t ed Resu l t s of Regression of To ta l Nitrogen and Nitrate and Ni t r i t e Nitrogen Unit-Area Loads and Flow-Weighted M e m Concent ra t ions

S e l e c t e d R e s u l t s of Regression of T o t a l K je ldah l and Ammonium Nitrogen, Unit-Area Loads and Flow-Weighted Mean Concent ra t ions

S e l e c t e d R e s u l t s of Regression of Potassium and Copper Unit- Area Loads and Flow-Weighted Mean Concent ra t ions

Se lec t ed R e s u l t s of Regression of Lead and Zinc Unit-Area Loads and Flow-Weighted Mean Concent ra t ions

Se lec t ed R e s u l t s of Regression of Endosulfan, A t raz ine and Po lych lo r ina t ed Biphenyls, Unit-Area Loads and Flow-Weighted Mean Concent ra t ions

Appendix

C - 1 Comparison of Measured and P r e d i c t e d Annual Loads of Suspended Sediments

C-2 Comparison of Measured With. P red ic t ed Annual Loads of T o t a l Phosphorus

C-3 Comparison of Measured and P red ic t ed Annual Loads of T o t a l Nitrogen

1 7

20

22

23

24

26

27

67

71

76

iii

LIST OF FIGURES Page

Number T i t l e

1

2

3

4

5

6

7

8

9

10

A-1

c- 1

c- 2

c- 3

c- 4

c- 5

C- 6

A g r i c u l t u r a l Regions of Southern Ontar io 6

Measured and P red ic t ed Values of Suspended Sediment f o r 10 PLUARG A g r i c u l t u r a l and 14 OMOE H i s t o r i c a l S i t e s 30

Measured and P red ic t ed Values of T o t a l Phosphorus f o r 10 PLUARG A g r i c u l t u r a l and 14 OMOE H i s t o r i c a l S i t e s 32

Unit-Area Loads of T o t a l Phosphorus From A g r i c u l t u r a l Land, Averaged Over A l l Rura l Land, as Estimated With a Regression Model 33

Measured and P red ic t ed Values of Ortho-Phosphorus f o r 10 PLUARG A g r i c u l t u r a l and 1 4 OMOE H i s t o r i c a l Si t 'es 34

Unit-Area Loads of Ortho-Phosphorus From A g r i c u l t u r a l Land, Averaged Over A l l Rura l Land, as Estimated With a Regression Model 36

Measured and P red ic t ed Values of T o t a l Nitrogen f o r 10 PLUARG A g r i c u l t u r a l and 14 OMOE H i s t o r i c a l S i t e s 37

Unit-Area Loads of T o t a l Nitrogen From A g r i c u l t u r a l Land, Averaged Over A l l Rural Land, as Estimated With a Regression Model 38

Measured and P r e d i c t e d Values of Nitrate & Nitr i te Nitrogen f o r 10 PLUARG A g r i c u l t u r a l and 1 4 OMOE H i s t o r i c a l S i t e s 39

Unit-Area Loads of Nitrate & Nit r i te Nitrogen From A g r i c u l t u r a l Land, Averaged Over A l l Rura l Land, as Estimated With a Regression Model 40

Appendix

Locat ions of PLUARG A g r i c u l t u r a l Watersheds i n Southern Ontario 45

Locat ions of A g r i c u l t u r a l Lands Having Unit-Area Loads as I n d i c a t e d of Suspended Sediment 69

Suspended Sediment Loads From A g r i c u l t u r a l Lands, Adjusted f o r Farm Land Density 70

Locat ions of A g r i c u l t u r a l Lands Having Unit-Area Loads as Ind ica t ed of T o t a l Phosphorus 73

T o t a l Phosphorus Loads From A g r i c u l t u r a l Land, a d j u s t e d f o r Farm Land Dens i ty 74

Lives tock Density and Estimated T o t a l Phosphorus Loads from Lives tock p e r Unit-Area of A l l Land 75

T o t a l Nitrogen Loads From A g r i c u l t u r a l Land, Adjusted f o r Farm Land Density 77

i v

ACKNOWLEDGEMENTS

The water q u a l i t y and q u a n t i t y da ta -ga ther ing ac t iv i t ies of the Water Resources Branch, Ontar io Min i s t ry of t h e Environment, and t h e coopera t ion of R.C. Ostry, R.C. Hore, R. Avadhanula, D. Onn and B. Bodo i n p a r t i c u l a r , are g r a t e f u l l y acknowledged. So a l s o is t h e work of R. Frank and B.D. Ripley of t h e P e s t i c i d e Residue Tes t ing Laboratory of the Ontar io Min i s t ry of Agr i cu l tu re and Food i n t h e surveying of t h e a c t i v i t i e s of facmers i n t h e s tudy areas.

The a u t h o r s a l s o wish t o acknowledge t h e c o n t r i b u t i o n s t o t h i s work of R.L. Leuty, J.F. Ramsey, D. M c D i l l and D. Skinner i n t h e p r e p a r a t i o n and a n a l y s i s of data .

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1 . 0 SUMMARY AND CONCLUSIONS

There has been a p e r s i s t e n t gap between t h e two most g e n e r a l l y a v a i l a b l e forms of in format ion on t h e e f f e c t s of a g r i c u l t u r e on water q u a l i t y . These two forms of in format ion are t h e r e s u l t s of small scale "plot" s t u d i e s and l a r g e scale r i v e r b a s i n o r l a k e loading ana lyses . The former are u s u a l l y l i m i t e d i n terms of v a r i a b i l i t y of s o i l , management and c l i m a t i c cond i t ions ; t h e l a t t e r g e n e r a l l y f a i l t o d i s t i n g u i s h between even d i s t i n c t l y d i f f e r e n t t ypes of a g r i c u l t u r a l ecvironments. The r e s u l t s of t h i s s tudy he lp t o b r idge t h e gap between t h e s e d i f f e r e n t approaches.

The r o l e of s o i l p a r t i c l e s i z e as a major i n f luence on t o t a l phosphorus, o rgan ic n i t rogen , z inc and a t r a z i n e loadings from a g r i c u l t u r a l l and has been c l e a r l y ind ica t ed . This ho lds important imp l i ca t ions i n terms of t h e e f f i c a c y of remedial measures i f they are s e l e c t e d wi thout r ega rd t o s o i l t ex tu re . I n c u l t i v a t e d areas, reduct ion of c u r r e n t l oad ings may be d i f f i c u l t t o achieve wi th s t anda rd remedial programs. Furthermore, l o s s e s of some of t h e s e materials from f ine - t ex tu red s o i l s may be unavoidable r e g a r d l e s s of t h e l and use p r a c t i c e employed.

The in f luence of source material a v a i l a b i l i t y on stream loadings of t h e more water s o l u b l e contaminants i n streams i s evidenced by t h e load ings of s o l u b l e ortho-phosphorus and n i t r a t e n i t r o g e n which can be accounted f o r t o a cons iderable degree by t h e i n p u t s ( f e r t i l i z e r and manure) of phosphorus and n i t r o g e n r e spec t ive ly . Endosulfan, a n example of t h e c u r r e n t l y used p e s t i c i d e s , w a s p re sen t i n r e l a t i o n t o t h e area of t h e c rops on which i t w a s used. can probably be expected i f i n p u t s are reduced.

Reductions i n loadings of t hese materials

The r e s u l t s i n d i c a t e that: some materials, such as PCB and copper, are e s s e n t i a l l y un re l a t ed t o m y aspec t of a g r i c u l t u r e . Control o r r educ t ions should n o t be expected through any remedial programs app l i ed t o a g r i c u l t u r a l a c t iv i t i e s .

P r e d i c t i o n equat ions based on s t a t i s t i ca l r eg res s ions of s t r e a m loadings on phys ica l and management c h a r a c t e r i s t i c s of t h e watersheds appear t o be f e a s i b l e f o r some water q u a l i t y parameters such as t o t a l and s o l u b l e ortho-phosphorus, t o t a l n i t rogen and n i t r a t e (p lus n i t r i t e ) n i t r o g e n . 'At tempts t o e x t r a p o l a t e r eg res s ion equat ions f o r sediment (suspended s o l i d s ) appear l ess s a t i s f a c t o r y . For most o t h e r parameters , t h e e x t r a p o l a t i o n of r eg res s ion equat ions would appear u n r e l i a b l e , though t h e occurrence of p e s t i c i d e s which a r e f a i r l y s p e c i f i c t o ce r t a in crops may be ex t r apo la t ed by cons ider ing t h e d i s t r i b u t i o n of t h e appropr i a t e c rops .

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2.0 INTRODUCTION -

During the w i n t e r of 1972-73, A g r i c u l t u r e Canada took i t s f i r s t s t e p towards t h e implementation of t h e Great Lakes Water Qua l i ty Agreement by s e t t i n g up a Task Force which reviewed t h e s t a t e of knowledge of t h e i n t e r r e l a t i o n s h i p s between a g r i c u l t u r e and water q u a l i t y i n t h e Canadian Great Lakes Basin. I n t h e i r r e p o r t on the a c t i v i t i e s of t h i s Task Force, Harris, Hore and MacLean (1973) reviewed e x t e n s i v e l y the information a v a i l a b l e from e x i s t i n g water q u a l i t y monitoring networks and d a t a on a g r i c u l t u r a l cropping and l i v e s t o c k product ion a c t i v i t i e s and p e s t i c i d e and f e r t i l i z e r useage i n t h e Canadian Great Lakes Basin. They found t h a t few si tes which were being monitored w i t h i n water q u a l i t y networks w e r e l o c a t e d i n such a way as t o f a c i l i t a t e t h e assignment of water q u a l i t y parameter l oad ing v a l u e s t o d i s t i n c t l y a g r i c u l t u r a l l and areas. Most s i tes were f o r sampling catchment areas which contained urban a c t i v i t y , and f r e q u e n t l y a sewage t reatment p l a n t was l o c a t e d a s h o r t d i s t a n c e upstream. Th i s w a s probably a r e f l e c t i o n of t h e o b j e c t i v e s of t h e e x i s t i n g monitoring networks which had p r i m a r i l y been intended € o r s u r v e i l l a n c e of known o r suspected sources of p o l l u t a n t material and f o r which a g r i c u l t u r a l l and had n o t been considered i n anything o t h e r than t h e broadest t e r m s . In s p i t e of t h i s c o n s t r a i n t on the a v a i l a b i l i t y of s u i t a b l e monitor ing d a t a , a t t empt s were made t o c h a r a c t e r i z e t h e p r i m a r i l y a g r i c u l t u r a l d ra inage b a s i n s , and comparisons wi th water q u a l i t y d a t a were made. Although n o t s t a t i s t i c a l l y s i g n i f i c a n t , t r e n d s were ev iden t which a s s o c i a t e d i n c r e a s e s i n t h e r a t i o of improved l and t o t o t a l land wi th i n c r e a s e s i n t h e concen t r a t ions of t o t a l and suspended s o l i d s i n streams. There w a s a l s o a tendency f o r higher e s t ima ted average rates of a p p l i c a t i o n of manure and f e r t i l i z e r n i t r o g e n t o be a s s o c i a t e d wi th h i g h e r concen t r a t ions of n i t r a t e - n i t r o g e n i n streams, b u t no r e l a t i o n s h i p could be d i sce rned between phosphorus concen t r a t ions and any of t h e e s t ima ted phosphorus useage parameters i n t h e watersheds.

Other more r ecen t s t u d i e s have a l s o run i n t o t h e problem of watershed d a t a being too g e n e r a l f o r i n f e r e n c e s t o be drawn regarding a g r i c u l t u r a l s o i l s o r p r a c t i c e s . McBean and Gorr ie (1975) concluded t h a t t h e m u l t i p l e l i n e a r r e g r e s s i o n approach t o analyzing non-point source p o l l u t i o n problems re la t ive t o t h e c h a r a c t e r i s t i c s of watershed areas (as used i n t h i s r e p o r t ) w a s v i a b l e , but t h a t a d d i t i o n a l d a t a c o l l e c t i o n w a s necessa ry i f t h e technique w a s t o be app l i ed s u c c e s s f u l l y . Ha i th (1976) a l s o a p p l i e d t h i s s t a t i s t i c a l approach t o New York watersheds, bu t a l s o r a n i n t o problems due t o t h e d i v e r s i t y of t h e watersheds and d i f f i c u l t y of d e s c r i b i n g them f u l l y . Omernik (1976), used a gene ra l a g r i c u l t u r a l / f o r e s t r y l u r b a n c l a s s i f i c a t i o n t o analyze a l a r g e q u a n t i t y of watershed load d a t a . s o broad t h a t e x t r a p o l a t a b l e v a l u e s could n o t be ob ta ined , even by geo log ic sub -ca t egor i za t ion .

The ove r l ap between ranges of v a l u e s i n each category w a s

Taken toge the r w i th o t h e r information e x t r a c t e d from a v a i l a b l e l i t e r a t u r e , Hore and MacLean’s r e s u l t s (Har r i s e t al., 1973) l e d them t o make, among o t h e r s , t he fol lowing recommendation:

“Se lec t ed a g r i c u l t u r a l watersheds should be monitored f o r t h e i r c o n t r i b u t i o n of n u t r i e n t s and any l i k e l y p o l l u t a n t s t o water. The si tes should be r e p r e s e n t a t i v e of va ry ing i n t e n s i t y of cropping and/or l i v e s t o c k e n t e r p r i s e s ; they should be no l a r g e r than r equ i r ed

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from hydro log ica l o r farming cons ide ra t ions so as t o arrive a t reasonably p r e c i s e n u t r i e n t budgets i nc lud ing l o s s e s t o water; .... 11

The recommendation went on t o sugges t coopera t ive p r o j e c t s between v a r i o u s agencies which would i n t e g r a t e s t u d i e s on p o l l u t a n t t r a n s p o r t p rocesses and a g r i c u l t u r a l management a l t e r n a t i v e s with the water q u a l i t y monitor ing. The recommendation f u r t h e r suggested t h a t t h i s approach should be considered f o r i n c l u s i o n i n t h e e f f o r t s of t he I n t e r n a t i o n a l Reference Group on Great Lakes P o l l u t i o n from Land Use Act ivi t ies (PLUARG), then i n i t s infancy .

In March 1973, t he PLUARG prepared i t s f i rs t Study Plan, which o u t l i n e d fou r d i s t i n c t t a s k s (known as Tasks A, B, C and D ) . Task C w a s descr ibed as:

" In t ens ive s t u d i e s of a small number of r e p r e s e n t a t i v e watersheds, s e l e c t e d and conducted t o permit some e x t r a p o l a t i o n of d a t a t o t h e e n t i r e Great Lakes Basin and t o relate contaminat ion of water q u a l i t y , which may be found a t r iver mouths on t h e Great Lakes, t o s p e c i f i c land uses and p r a c t i c e s . "

A c t i v i t y 1 of Task C (Canada) w a s f u r t h e r i d e n t i f i e d as " P i l o t Agri- c u l t u r a l Watershed Surveys", and descr ibed as fo l lows:

" In t ens ive s t u d i e s on a s e l e c t i o n of r e p r e s e n t a t i v e watersheds and i n some cases of subwatersheds wi th in s e l e c t e d watersheds, are needed t o provide i n f o m a t i o n on output and p ropor t ions of y i e l d s of n u t r i e n t s , sediment and p e s t i c i d e s i n p a r t i c u l a r s p e c i f i c sources ." (S ic)

During t h e pe r iod from t h e summer 1973 t o 1977, t h e A g r i c u l t u r a l Watershed S t u d i e s were planned, implemented i n two phases and then i n t e g r a t e d along l i n e s similar t o those suggested i n t h e recommendation of Ilore and MacLean (Har r i s e t a l . , 1973). The s u b j e c t of t h i s r e p o r t i s t h e "overview" a n a l y s i s of t h e monitor ing d a t a c o l l e c t e d during t h e 1975-1977 i n t e n s i v e s tudy phase of t h e A g r i c u l t u r a l Watershed Studies . The r e p o r t o u t l i n e s t h e methodology and r a t i o n a l f o r t h e s e l e c t i o n of s u i t a b l e monitor ing s i tes , t h e methods used f o r water q u a l i t y and q u a n t i t y d a t a a c q u i s i t i o n , t h e e s t ima t ion of watershed c h a r a c t e r i s t i c s , and t h e s t a t i s t i c a l ana lyses of t h e va r i ance w i t h i n t h e d a t a sets. F i n a l l y , some conclusions are drawn which are app l i ed t o an e x t r a p o l a t i o n model which a t tempts t o determine a r e a s of t h e lower Canadian Great Lakes Basin which f a l l i n t o s e l e c t e d ranges of p o l l u t a n t c o n t r i b u t i o n rates t o streams.

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3 . 0 METHODS AND PROCEDURES

During t h e f a l l and win te r of 1973-74, d a t a w e r e prepared by which r a t i o n a l s e l e c t i o n s could be made of sites which would m e e t t h e requi re - ments of r ep resen ta t iveness of t h e major d i f f e r e n t i a b l e a g r i c u l t u r a l l and use areas of t h e Canadian Great Lakes Basin.

The procedures followed, t h e eva lua t ions made and t h e r e s u l t i n g s e l e c t i o n s of " a g r i c u l t u r a l regions" and " r e p r e s e n t a t i v e sub-watersheds" are descr ibed i n "Agr i cu l tu ra l Land Uses, Livestock and S o i l s of t h e Canadian Great Lakes Basin, a Report of t h e A c t i v i t i e s of t h e Engineering Research Se rv ice and t h e S o i l Research I n s t i t u t e as p a r t of Agr i cu l tu re Canada's Cont r ibu t ion t o t h e Implementation of t h e Great Lakes Water Qual i ty Agreement, 1973-74" (Coote, MacDonald and Wall; 1974). For t h e purposes of t h i s r e p o r t , t h e fol lowing summary of t h e s e procedures i s included:

The " a g r i c u l t u r a l " po r t ion of t h e Great Lakes Basin w a s separa ted from t h e remainder on t h e b a s i s of t h e presence of s i g n i f i c a n t a g r i c u l t u r a l l and use. I n practice, t h i s meant t h a t only t h a t p o r t i o n of t h e b a s i n below t h e 45th para l le l w a s considered i n f u r t h e r ana lyses .

A s o i l map w a s prepared which sepa ra t ed s o i l types according t o t h e i r p o t e n t i a l t o t r a n s p o r t p o l l u t a n t s ( i f p re sen t ) t o su r face o r ground water. This c l a s s i f i c a t i o n of s o i l s recognized high, medium and low p o t e n t i a l s t o s u r f a c e and ground water, and r e s u l t e d i n 5 o rde r s of p o t e n t i a l , which were subdivided i n t o 3 major s o i l t e x t u r e groups, with a d d i t i o n a l groups f o r shallow o r organic s o i l s . The c r i t e r i a f o r t h e inc lus ion of each s o i l series i n a p a r t i c u l a r P o l l u t a n t T rans fe r P o t e n t i a l group included s lope , permeabi l i ty (based p r imar i ly on t e x t u r e and s t r u c t u r e ) , d ra inage class, and depth. w a s c l a s s i f i e d according t o t h i s system by t h e l eade r of t h e S o i l Survey P r o j e c t (C.J. Acton, P r o j e c t Leader, A g r i c u l t u r a l Watershed P r o j e c t 7 - S o i l Survey, Ontar io S o i l Survey Unit , Agr i cu l tu re Canada, Guelph), and a composite s o i l map of t h e area w a s prepared.

Each of t h e s o i l series i n t h e des igna ted a g r i c u l t u r a l area

Cl imat ic d a t a were considered, inc luding f r o s t - f r e e pe r iod , growing degree days, corn h e a t u n i t s and p r e c i p i t a t i o n . The area w a s subsequent ly d iv ided i n t o two major c l i m a t i c r eg ions , -viz . t h e lower e l e v a t i o n reg ions c l o s e s t t o t h e l a k e shores wi th longer f r o s t - f r e e pe r iods and h igher h e a t u n i t s , and t h e coo le r , h igher p r e c i p i t a t i o n zone of t h e Dundalk uplands encompassing parts of Bruce, Duffer in , Grey, Huron, Pe r th and Wellington Counties.

Census of Agr i cu l tu re d a t a (1971) w e r e prepared and mapped, by t h e SYMAP computer mapping procedure, t o g ive a d i s t r l b u t i o n p a t t e r n f o r each of t h e major c rops and l i v e s t o c k types of t h e basin. Estimates w e r e made of t h e usage of f e r t i l i z e r s and manure n u t r i e n t s and t h e p a t t e r n s w e r e a l s o mapped.

When t h e r e s u l t s of t h e fou r procedures summarized above w e r e combined, twenty-one f a i r l y de f inab le a g r i c u l t u r a l r eg ions emerged, w i th boundaries fo l lowing c l o s e l y t h e major changes i n s o i l p o l l u t a n t t r a n s f e r p o t e n t i a l

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groups , These reg ions are shown i n F igure 1. 85% of t h e a g r i c u l t u r a l p a r t of t h e Canadian Great Lakes Basin. remaining areas are e i t h e r urban land (such as Toronto and Hamilton a r e a s ) o r are complexes of a g r i c u l t u r a l s o i l s and cropping which were n o t s u f f i c i e n t l y uniform t o be ca t egor i zed as an " a g r i c u l t u r a l area". These la t ter areas w e r e t r e a t e d as mixtures of t h e o t h e r areas i n t h e e x t r a p o l a t i o n s d iscussed l a t e r i n t h i s r epor t .

They cover approximately The

Maps and a i rpho tos were then searched f o r s m a l l watersheds i n each of t h e s e a g r i c u l t u r a l reg ions . Area 21, t h e o rgan ic s o i l s of t h e Bradford-Holland marsh w e r e excluded because of e x i s t i n g monitor ing be ing c a r r i e d o u t i n t h e Er ieau marsh (Mi l l e r , 1974) and s t u d i e s being planned f o r t h e organic s o i l area of northwestern New York. areas s u i t a b l e f o r monitor ing were sought which were i n t h e range of 20-50 km2. s t a b l e wi th few pe r iods of zero o r excess ive ly high (unmonitorable) f low, and y e t small enough t o s t i l l enable t h e d e f i n i t i o n of t he a g r i c u l t u r a l c h a r a c t e r i s t i c s , based on reasonably homogenious areas, f r e e of un re l a t ed non-ag r i cu l tu ra l l and uses . A f t e r a s m a l l number of p o t e n t i a l monitor ing si tes were l o c a t e d , maps of t h e dra inage sub-basins upstream of each s i t e w e r e prepared, and t h e si tes v i s i t e d t o select t h e most d e s i r a b l e i n each case on t h e b a s i s of t h e ease of sampling and f low measurement, t h e absence of non-ag r i cu l tu ra l a c t iv i t i e s n o t seen on t h e a i rpho tos and t h e gene ra l appearance of t h e sub-basin as " rep resen ta t ive" of t h e a g r i c u l t u r a l reg ion .

Drainage

This s i z e w a s considered l a r g e enough t o be hydro log ica l ly

Seventeen si tes w e r e s e l e c t e d and monitored from March 1974 t o October 1974 (no s u i t a b l e si tes w e r e found i n a g r i c u l t u r a l areas 17, 18, and 2 0 , and i t w a s concluded t h a t t h e program would n o t s u f f e r by exc lus ion of t h e s e areas as sampling resources were a l r e a d y over-extended). A coopera t ive agreement was reached wi th t h e Ontar io Minis t ry of t h e Environment t o i n s t a l l s t a f f gauges, c o l l e c t water samples (grab sampling) and conduct r o u t i n e water q u a l i t y ana lyses . phosphorus forms ( t o t a l , t o t a l d i s so lved , s o l u b l e ortho-P) , fou r n i t r o g e n forms (Tota l Kje ldahl , n i t r a t e , n i t r i t e , d i s so lved ammonia), suspended s o l i d s , t o t a l and o rgan ic carbon, potassium, calcium, sodium, c h l o r i d e , su lpha te , and a number of trace elements (Pb, Zn, Cu, Hg, C r , Fe, A l , N i , A s , C a , Bo). A s i m i l a r agreement w a s reached w i t h t h e Ontar io Min i s t ry of Agr i cu l tu re and Food and t h e London Research I n s t i t u t e of Agr i cu l tu re Canada t o conduct ana lyses f o r s e l e c t e d i n s e c t i c i d e s and h e r b i c i d e s . The Ontar io S o i l Survey Unit of Agr i cu l tu re Canada conducted an e v a l u a t i o n of t h e s o i l e ros ion p o t e n t i a l of each of t h e s e monitored sub- wa te r s heds .

These included t h r e e

A f t e r t h e six-month per iod of i n i t i a l monitor ing and obse rva t ion , t h e d a t a w e r e eva lua ted and some s i tes were found t o be unsu i t ab le . The most common problem w a s t h a t of ob ta in ing r e l i a b l e estimates of flow, whi le secondary problems a r o s e where watersheds were found t o be less r e p r e s e n t a t i v e of t h e a g r i c u l t u r a l areas than previous ly thought . C o n s t r a i n t s i n sampling and flow measurement r e sources were a l s o considered, t o g e t h e r wi th t h e need f o r more i n t e n s i v e sampling a t most l o c a t i o n s . Eleven a g r i c u l t u r a l areas were f i n a l l y s e l e c t e d f o r cont inued monitor ing, f o r which fou r sites were considered adequate (AG-1, 3 , 4, and 5 ) . To

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e s t a b l i s h t h e remaining seven s i t e s , t h e s e l e c t i o n procedure involv ing a i r p h o t o i n t e r p r e t a t i o n and ground surveys w a s repea ted . I n one case , t h e monitor ing s i t e was s h i f t e d upstream a s h o r t d i s t a n c e t o t ake advantage of b e t t e r f low monitor ing cond i t ions (AG-10); fou r o t h e r s i t e s w e r e re - loca ted on d i f f e r e n t branches of t h e same stream t o g ive improved monitor ing c a p a b i l i t y (AG-2, 11, 13 and 1 4 ) ; and two s i t e s w e r e moved t o a new dra inage b a s i n e n t i r e l y (AG-6 and 7 ) . The se l ec . t i on procedures a r e d iscussed i n more d e t a i l i n Sec t ion I of t h e Annual Report of t h e A g r i c u l t u r a l Watershed S tud ie s f o r 1974-75 (Agric. Sub-Comm., 1975).

From March of 1975 t o t h e end of A p r i l 1977, t h e e leven s i t e s were sampled r e g u l a r l y a t least once [ler week. S ix of t h e s i t e s monitor ing watersheds, i d e n t i f i e d a s loca t icms s u i t a b l e f o r more i n t e n s i v e s t u d i e s of p o l l u t a n t t r a n s p o r t and t ransformat ions , were instrumented with au tomat ic pumping samplers (C.A.E. A i r c r a f t L td . , Winnipeg, Man., Model 304) designed t o sample on a t i m e o r s t a g e he igh t a c t i v a t i o n b a s i s . The mechanisms w e r e set t o sample d a i l y except when flow even t s took p l ace , when samples were col. lected more f r equen t ly . A l l s i t e s were equipped wi th cont inuous-recording flow s tage-he ight recorders .

Samples were c o l l e c t e d and t r anspor t ed by t h e Ontar io Minis t ry of t h e Environment t o t h e i r l a b o r a t o r i e s a t Rexdale o r London, Ontar io . Complete d e s c r i p t i o n s of sampling methods, s a m p l e handl ing procedures , and l a b o r a t o r y ana lyses are t o be found in : "Work Plan , Task Group C (Canadian S e c t i o n ) , A c t i v i t i e s l., 3 and 4 S t u d i e s , I n t e r n a t i o n a l Reference Group on Great Lakes P o l l u t i o n from Land U s e A c t i v i t i e s , I n t e r n a t i o n a l J o i n t Commission" [Ontar io Minis t ry of t h e Environment, 1976).

A number of methods have been used t o o b t a i n information on the c h a r a c t e r i s t i c s of t h e watersheds. The primary sources of information w e r e t h e farm-by-farm survey of a g r i c u l t u r a l p r a c t i c e s conducted by t h e Ontar io Min i s t ry of Agr i cu l tu re and Food (Frank and Ripley, 1977) , and t h e d e t a i l e d i n s p e c t i o n of s o i l maps and 1:50,000 topographica l maps.

Water q u a l i t y and q u a n t i t y d a t a w e r e processed as rece ived by u t i l i z i n g t h e Environment Canada water q u a l i t y d a t a bank (NAQUADAT). Output from t h i s system w a s by way of summaries, p l o t s , means, r eg res s ions , and cumulat ive loadings . Users Manual" (DeMayo and Hunt, 1975). Equations desc r ib ing t h e r e g r e s s i o n of water q u a l i t y pa rane te r concen t r a t ions on flow were used t o make estimates of concen t r a t ions t o f i l l gaps i n t h e record (missing d a t a ) and t o c o r r e c t t h e loading c a l c u l a t i o n a t p o i n t s i n t i m e when flow changed s i g n i f i c a n t l y (usua l ly an inc rease o r decrease of more than about 2 0 % ) , bu t no s a m p l e s w e r e c o l l e c t e d . Loadings were d iv ided by watershed areas t o o b t a i n u n i t a r e a loadings , and by t o t a l f low t o o b t a i n flow-weighted mean concent ra t ions . These va lues f o r each watershed, t oge the r wi th t h e d a t a on the c h a r a c t e r i s t i c s of each watershed, w e r e input t o a computerized s t e p w i s e m u l t i p l e l i n e a r r eg res s ion procedure developed by t h e Engineer ing and S t a t i s t i c a l Research Serv ice of Agr i cu l tu re Canada. matrices, and t h e 100 combinations of parameters w i th t h e h ighes t r va lues us ing one, two o r t h r e e independent v a r i a b l e s a t a t i m e . Following

The methods used a r e descr ibed i n t h e "NAQUADAT

Output was i n t h e form o f c o r r e l a t i o n c o e f f i c i e n t 2

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t h i s v a r i a b l e s e l e c t i o n technique, t h e s e l e c t e d d a t a w e r e i npu t t o a t e rmina l ope ra t ed computer package and run through m u l t i p l e l i n e a r and polynomial r eg res s ion procedures t o determine t h e s t a t i s t i c a l s i g n i f i c a n c e of v a r i a b l e s and t o o b t a i n t h e c o e f f i c i e n t s f o r s u i t a b l e p r e d i c t i v e equat ions .

The e x t r a p o l a t i o n of un i t - a rea and flow-weighted mean concent ra t ion d a t a t o t h e remainder of t h e Canadian Great Lakes Basin w a s then t e s t e d by comparing p red ic t ed wi th measured va lues a t a s m a l l number of predominantly a g r i c u l t u r a l watersheds which are r o u t i n e l y monitored by t h e On ta r io Min i s t ry of t h e Environment as p a r t of i t s Water Qual i ty Monitoring network and which a l s o have Water Survey of Canada f low gauging a t , o r nearby, t h e sampling sites. Data were obta ined from t h e Ontar io Min i s t ry of t h e Environment (1964-74), and from t h e Water Survey of Canada (1964-74). P red ic t ed va lues were a l s o compared with OMOE monitor ing d a t a c o l l e c t e d under t h e PLUARG program a t predominantly a g r i c u l t u r a l s e c t o r s of t h e Grand and Saugeen Rivers (Hore and Ost ry , 1978 a and b) . Following t h i s rocedure, t h e b e s t p r e d i c t i v e equa t ions

i n d i v i d u a l independent v a r i a b l e s , and a v a i l a b i l i t y of da ta . were s e l e c t e d on t h e b a s i s of r 5 va lues , s t a t i s t i c a l s i g n i f i c a n c e of

Census of Agr i cu l tu re d a t a , c o l l e c t e d i n 1971, were used t o estimate t h e va lues of independent v a r i a b l e s , us ing t h e Canada Land Inventory computerized Geographic Information System t o over lay Water Survey of Canada watershed sub-basins (subdivided f u r t h e r i n some i n s t a n c e s ) upon t h e boundaries of Census Enumeration Areas. A t a p e of 1 9 7 1 a g r i c u l t u r a l census da t a , on an enumeration area b a s i s , w a s then accessed t o extract va lues of each appropr i a t e v a r i a b l e . were updated t o r e f l e c t 1976 va lues by applying, county by county, c o r r e c t i o n f a c t o r s t o r e f l e c t t h e change wi th t i m e over t h e 1971 t o 1976 per iod . The f a c t o r s were obta ined by comparing county d a t a from t h e Ontar io A g r i c u l t u r a l Census f o r t h e s e two y e a r s (Ontar io Minis t ry of A g r i c u l t u r e and Food, 1972 and 1977) , and determining t h e percent i n c r e a s e o r decrease i n t h e area grown i n each county of each crop type and i n t h e number of animals r a i s e d .

These v a r i a b l e s

F i n a l l y , t h e watershed dra inage bas in boundaries were mapped. These were developed from Water Survey of Canada maps and modified by a d d i t i o n a l sub-d iv is ion t o meet PLUARG o b j e c t i v e s . The Val-ies o f major p o l l u t a n t s generated from t h e a p p l i c a t i o n of t h e p r e d i c t i o n equat ions were then p l o t t e d on t h e s e maps t o g ive a d i s t r i b u t i o n p a t t e r n of p o t e n t i a l l oad ing rates of s e l e c t e d p o l l u t a n t s t o streams from a g r i c u l t u r a l land.

A f u r t h e r e x t r a p o l a t i o n w a s made, us ing procedures s e l e c t e d by o t h e r p a r t i c i p a n t s i n t h e PLUARG A g r i c u l t u r a l Watershed S t u d i e s , t o t h e e n t i r e Great Lakes Basin. The r e s u l t s of t h i s a c t i v i t y , c a r r i e d out f o r t h e r e p o r t prepared by t h e Task C Syn thes i s and Ext rapola t ion Work Group (Ches te rs -- e t a l . , 1978) , appear i n t h e Appendix.

4.0 RESULTS

4 . 1 Pre l iminary Analyses

A number of ana lyses were conducted on t h e d a t a by way of pre l iminary e l i m i n a t i o n of al ternative approaches and checking t h e v a l i d i t y of da t a . Many of these ana lyses have been desc r ibed i n prev ious progress r e p o r t s of t h i s p r o j e c t (Coote, 1975; Coote and Leuty, 1976 a and b) and w i l l n o t be repea ted i n t h i s f i n a l r e p o r t . of t h e s e ana lyses fol lows.

A b r i e f d i s c u s s i o n of t h e r e s u l t s

4 . 1 . 1 V a l i d i t y of NAQUADAT load ings

A comparison w a s c a r r i e d ou t between loading v a l u e s c a l c u l a t e d by t h e NAQUADAT method wi th those suppl ied by OMOE, c a l c u l a t e d by t h e Beale Ra t io Es t imator method. NAQUADAT load ings w e r e a l s o c a l c u l a t e d a f t e r a "missing da ta" c o r r e c t i o n w a s employed. This w a s achieved by determining t h e equa t ions t o t h e l i n e of b e s t f i t r e l a t i n g concen t r a t ions wi th f low (d i scha rge ) . The d a i l y d a t a were then searched f o r days on which stream f low changed by more than 20% (approximately) without a sample being c o l l e c t e d . On t h e s e occas ions , t h e concen t r a t ion w a s es t imated from t h e l i n e a r r e l a t i o n s h i p wi th f low, and these estimates were recorded i n t h e NAQUADAT system f o r use i n loading c a l c u l a t i o n s . This procedure was followed f o r t h e t h r e e phosphorus forms and f o r suspended s o l i d s - t h e s e be ing parameters which are h igh ly flow-dependent and f o r which s u f f i c i e n t d a t a e x i s t e d fo r t h e s e estimates t o be reasonably made.

C o r r e l a t i o n c o e f f i c i e n t s between NAQUADAT and Beale R.E. loadings ranged from 0.83 f o r suspended :sol ids t o 0.98 f o r n i t r a t e p l u s n i t r i t e - n i t rogen . Comparison wi th t h e r e s u l t s of t h e i n v e s t i g a t i o n of P r o j e c t s 16 and 1 7 (Erosion Losses and Sediment Del ivery Ra t ios ) i n d i c a t e d t h a t t h e NAQUADAT loadings , w i th est.imates, were t h e most r e l i a b l e v a l u e s f o r suspended s o l i d s - t h e most d i f f i c u l t parameter co measure a c c u r a t e l y as loadings (Van V l i e t , Wall and Dickinson, 1978) . t h e NAQUADAT loading d a t a base was t h e r e f o r e accepted.

The v a l i d i t y of

4 . 1 . 2 Seasonal Var i a t ion

An a n a l y s i s of seasonal t r ends i n loads and concen t r a t ions compared wi th c o r r e l a t e d independent v a r i a b l e s w a s a l s o c a r r i e d o u t . This a n a l y s i s w a s both inconclus ive and incomplete. v a r i a t i o n i n month t o month c o r r e l a t i o n s wi th independent v a r i a b l e s , b u t t h e r e w a s a tendency f o r t h e group of vcrr iables which w a s b e s t c o r r e l a t e d t o remain s i g n i f i c a n t i n a l l months, - b u t w i th vary ing ranking. PLUARG f o r t o t a l annual loadings t o t h e Great Lakes. I n o t h e r words, PLUARG intended t o pursue t h e loading problem of t h e Lakes themselves on a "Total Annual Load" b a s i s , and t h i s gave weight t o t h e d e c i s i o n t o concen t r a t e on i n v e s t i g a t i o n s of r e l a t i o n s h i p s between a g r i c u l t u r a l l and use and annual stream loadings . The f i e l d of i n v e s t i g a t i o n involv ing seasona l l oads i n PLUARG a g r i c u l t u r a l watershed d a t a remains open f o r f u r t h e r work.

There w a s cons iderable

Coupled wi th t h i s f i n d i n g w a s t h e concern expressed w i t h i n

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4.2 C o r r e l a t i o n and Regression Analys is

The d a t a which have been c o l l e c t e d and which were used i n t h e s t a t i s t i c a l ana lyses are presented i n t h e appendix. The c o r r e l a t i o n c o e f f i c i e n t matrices f o r un i t - a rea l o a d s and flow-weighted mean concen- t r a t i o n s are a l s o presented i n t h e appendix. A l l " loadst t and "concentrat ions" r e f e r r e d t o i n t h i s d i scuss ion are un i t - a rea loads and flow-weighted mean concen t r a t ions , r e s p e c t i v e l y . C o r r e l a t i o n s among v a r i a b l e s w i l l be d iscussed below, f i r s t by watershed c h a r a c t e r i s t i c s , then by water q u a l i t y parameters and f i n a l l y t h e c o r r e l a t i o n s between t h e s e two groups. (A l l c o r r e l a t i o n s s i g n i f i c a n t a t p 5 0.05 u n l e s s o therwise s t a t e d ) .

4 . 2 . 1 C o r r e l a t i o n s among watershed c h a r a c t e r i s t i c s

It i s important t o look a t c o r r e l a t i o n s among watershed cha rac t e r - i s t i c s , a s t h e s e may exp la in some aspec t s of t h e c o r r e l a t i o n s observed between watershed c h a r a c t e r i s t i c s and water q u a l i t y parameters . There i s a need t o remain aware of t h e p o t e n t i a l f o r m i s i n t e r p r e t a t i o n of such c o r r e l a t i o n s , and t o compare r e s u l t s with r a t i o n a l hypotheses , r a t h e r than accep t a l l r e l a t i o n s h i p s which appear t o be s t a t i s t i c a l l y s i g n i f i c a n t .

- Area (AR): There is a tendency (not s t a t i s t i c a l l y s i g n i f i c a n t ) f o r area t o be r e l a t e d wi th woodland. This is because t h e l a r g e r watersheds had more woodland, e s p e c i a l l y watersheds 2 and 7.

2 Cul t iva t ed (CL): The watershed c h a r a c t e r i s t i c s which are s t a t i s t i c a l l y c o r r e l a t e d wi th c u l t i v a t e d land included f e r t i l i z e r use (both n i t rogen and phosphorus), t o t a l phosphorus i n p u t s ( f e r t i l i z e r p lus manure), t h e d e n s i t y of t i l e d r a i n s and t o t a l row crops .

S o i l Clay Content (SC): Clay conten t was s t r o n g l y c o r r e l a t e d wi th t h e index of p o l l u t a n t t r a n s f e r p o t e n t i a l t o s u r f a c e water, which might be expected as i t was i n p a r t a determinant of t h i s index, and nega t ive ly c o r r e l a t e d wi th woodland and tobacco a rea .

S o i l Sand Content (SA) : Sand content w a s nega t ive ly c o r r e l a t e d wi th t h e index of p o l l u t a n t t r a n s f e r p o t e n t i a l t o s u r f a c e water and p o s i t i v e l y c o r r e l a t e d wi th t h a t t o ground water f o r t h e same reason mentioned above f o r so i l - c l ay . S o i l e x t r a c t a b l e phosphorus w a s s t r o n g l y c o r r e l a t e d with sand con ten t , probably because of t h e high f e r t i l i z e r a p p l i c a t i o n s i n sandy watersheds 2 and 1 3 where tobacco i s grown. Three c l o s e l y r e l a t e d watershed c h a r a c t e r i s t i c s , -animal u n i t s , manure n i t rogen and manure phosphorus were nega t ive ly c o r r e l a t e d with s o i l sand. r e s u l t appears t o r e f l e c t t h e use of On ta r io ' s sandy s o i l s f o r tobacco, vege tab le s and orchards where l i v e s t o c k d e n s i t i e s are low.

This

Erosion p o t e n t i a l (EP): Erosion p o t e n t i a l w a s developed from t h e a p p l i c a t i o n of t h e Universal S o i l Loss Equat ion t o t h e e leven . .

watersheds . l b u t i t was a l s o c o r r e l a t e d wi th pe rcen t n o n a g r i c u l t u r a l l and . appears t o be an anomaly r e s u l t i n g from t h e coincidence of non-ag r i cu l tu ra l l and and a high e r o s i o n p o t e n t i a l i n Watershed 13. an i n t e n s i v e l y c u l t i v a t e d area wi th t h e h ighes t d e n s i t y of r e s idences and o t h e r non-farmed areas. wi th f e r t i l i z e r n i t rogen use and t i l e d r a i n s - probably by way of t h e i n t e r r e l a t i o n s h i p s wi th row crops .

It w a s c o r r e l a t e d wi th row crops , as might be expected, This

Watershed 1 3 is

Erosion p o t e n t i a l w a s a l s o c o r r e l a t e d

'Prepared by G . J . Wall and L.J.P. van V l i e t , Agr i cu l tu re Canada, Ontar io S o i l Survey, Guelph.

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P o l l u t a n t Transpor t P o t e n t i a l t o Surface Waters (PS) : This d imens ionless index of t h e p r o b a b i l i t y of s u r f a c e water movement t o streams w a s r e l a t e d t o two c h a r a c t e r i s t i c s o t h e r than s o i l t e x t u r e . There w a s a nega t ive c o r r e l a t i o n wi th woodland and s o i l e x t r a c t a b l e phosphorus, which appears t o r e f l e c t t h e h igh woodland and s o i l e x t r a c t a b l e phosphorus found i n Watershed 2 , where the s u r f a c e water t r a n s f e r p o t e n t i a l w a s very low.

P o l l u t a n t Transpor t P o t e n t i a l t o Groundwater (PG): This index is s t r o n g l y c o r r e l a t e d wi th soi l . sand con ten t , and nega t ive ly c o r r e l a t e d wi th l i v e s t o c k and manure n u t r i e n t s , - f o r the same reason as given under the d i s c u s s i o n of sand con ten t above.

Stream d e n s i t y (SD): This c h a r a c t e r i s t i c appeared t o be independent of all o t h e r s measured or e s t i m a t e d i n t h i s s tudy.

Rural Residences (RR): It is assumed he re t h a t the primary impac t , i f any, of r u r a l r e s idences would be by way of t he e t f e c t of sep t ic tanks on water q u a l i t y . Rural r e s idences were c o r r e l a t e d wi th vege tab le s , o rcha rds , non-ag r i cu l tu ra l land and f e r t i i i z e r phosphorus use - a l l of which are n o t i c e a b l y h igh i n Watershed 13 where t h e h i g h e s t d e n s i t y of r u r a l r e s idences is found. This a s s o c i a t i o n i s one which must be cons idered i n any r e l a t i o n s h i p involving r u r a l r e s idences .

Road Density (RD) : This c h a r a c t e r i s t i c appeared t o be independent of a l l o t h e r s except non-ag r i cu l tu ra l land.

Row Crops (RC): A s w e l l as being c o r r e l a t e d wi th c u l t i v a t e d land and each of tile c h a r a c t e r i s t i c s wi th which t h i s w a s c o r r e l a t e d , row crops were a l s o r e l a t e d t o corn and vege tab le a r e a s .

Corn Area (CA): Corn area w a s c o r r e l a t e d w i t h f e r t i l i z e r n i t r o g e n , t o t a l n i t r o g e n ( f e r t i l i z e r p l u s manure) and t i l e dra inage d e n s i t y .

Soybeans (SY): Soybeans were c o r r e l a t e d w i t h row c rops and f e r t i l i z e r n i t rogen . a s s o c i a t i o n of f e r t i l i z e r i n p u t s w i t h r o w c rops , as i t w o u l d otherwise be unreasonable.

The la t ter c o r r e l a t i o n i s almost c e r t a i n l y the r e s u l t of the

Tobacco (TO): This w a s s t r o n g l y c o r r e l a t e d wi th s o i l sand con ten t and p o l l u t a n t t r a n s f e r p o t e n t i a l t o groundwater.

Vegetables and Orchards (VA, OR): These two crops were c l o s e l y c o r r e l a t e d wi th each o t h e r and wi th f e r t i l i z e r i n p u t s and t i l e drainage d e n s i t y . The tendency f o r most of tne vege tab le s and orchards i n t h e s tudy areas t o be found i n Watershed 13 must be cons idered when these c rops are inc luded i n any p r e d i c t i v e equat ion.

Cereals (CC): Cereals were n o t c o r r e l a t e d wi th any c h a r a c t e r i s t i c o t h e r than exposed streambank - a r e l a t i o n s h i p which cannot be r e a d i l y explained.

- 12 -

P a s t u r e and Hay (PA): P a s t u r e and hay w a s s t r o n g l y n e g a t i v e l y This c h a r a c t e r i s t i c c o r r e l a t e d wi th row crops and c u l t i v a t e d land.

w a s t h e r e f o r e nega t ive ly c o r r e l a t e d wi th many of t h e c h a r a c t e r i s t i c s which were p o s i t i v e l y c o r r e l a t e d wi th row crops and c u l t i v a t e d land. It w a s a l s o p o s i t i v e l y c o r r e l a t e d w i t h animal u n i t s .

Woodland (WA): There w a s a tendency (not s t a t i s t i c a l l y s i g n i f i c a n t ) f o r woodland t o be n e g a t i v e l y c o r r e l a t e d wi th most crops and i n p u t s such as f e r t i l i z e r and manure.

Non-agr icu l tura l Land (NA): Th i s c h a r a c t e r i s t i c w a s h i g h e s t i n Watershed 13, and t h i s r e s u l t e d i n some spur ious c o r r e l a t i o n s wi th orchards and vege tab le s , which are n o t o the rwise exp la inab le .

Animal Units (AU): Manure n u t r i e n t s and p a s t u r e and hay were s t r o n g l y c o r r e l a t e d wi th animal u n i t s , which i s h a r d l y s u r p r i s i n g .

S o i l E x t r a c t a b l e Phosphorus (SP): Th i s c h a r a c t e r i s t i c w a s a r r i v e d a t by estimates from county average NaHC03 e x t r a c t a b l e P va lues by crop type. It w a s p o s i t i v e l y c o r r e l a t e d wi th f e r t i l i z e r i n p u t s , row crops, tobacco, and vege tab le s . parameters, of which f e r t i l i z e r P and sandy s o i l s seem t o be dominant.

It appears t o r e f l e c t a composite of many

Slope (AG): This c h a r a c t e r i s t i c w a s n o t s i g n i f i c a n t l y c o r r e l a t e d w i t h any o t h e r which may r e f l e c t t h e d i f f i c u l t y of applying a mean va lue of t h i s c h a r a c t e r i s t i c t o an e n t i r e watershed.

Exposed Streambank (ES): This estimate of unvegetated streambank (made by K. Knap i n t h e streambank e r o s i o n s t u d y ) , w a s c o r r e l a t e d only wi th cereal crops which remains unexplained.

T i l e Drainage Density (TD): The estimates of t i l e dra inage d e n s i t i e s w e r e made by O.M.A.F. A g r i c u l t u r a l Extension Engineers. The va lues were c o r r e l a t e d wi th f e r t i l i z e r i n p u t s , row crops, c u l t i v a t e d land, corn and vege tab le s .

F e r t i l i z e r Nitrogen (FN), Phosphorus (FP), and Potassium (FK): These t h r e e i n p u t c h a r a c t e r i s t i c s were s t r o n g l y c o r r e l a t e d one wi th the o t h e r , and wi th c u l t i v a t e d land , row c rops , vege tab le s and wi th t h e s o i l e x t r a c t a b l e phosphorus index. I n a d d i t i o n , f e r t i l i z e r n i t r o g e n w a s c o r r e l a t e d wi th corn area. Negative c o r r e l a t i o n s a l s o e x i s t e d wi th p a s t u r e and hay land.

Manure n i t r o g e n (MN), Phosphorus ( M P ) and Potassium (MK): Estimates were made of t h e q u a n t i t y of n u t r i e n t s conta ined i n manure genera ted by t h e l i v e s t o c k i n each watershed. These v a l u e s w e r e c o r r e l a t e d wi th animal u n i t s and p a s t u r e and hay.

T o t a l Nitrogen (TN), Phosphorus (TP) and Potassium (TK): The va lues used f o r t h e s e c h a r a c t e r i s t i c s were t h e combination of t h e f e r t i l i z e r and manure i n p u t s d i scussed above. I n gene ra l , t h e f e r t i l i z e r va lues dominated, i n t h a t most of t h e c o r r e l a t i o n s wi th t h e f e r t i l i z e r n u t r i e n t s were a l s o seen wi th t h e t o t a l n u t r i e n t s .

- 13 -

P r e c i p i t a t i o n (PP): T o t a l p r e c i p i t a t i o n ( r a i n f a l l p l u s snow) w a s cons idered as a v a r i a b l e , bu t then omi t ted due t o t h e ve ry small v a r i a t i o n on a mean annual b a s i s between t h e sites i n t h e 2 yea r pe r iod of t h e s tudy (range from 803 t o 920 mm/yr).

4.2.2 C o r r e l a t i o n s among water q u a l i t y parameter loads and flow weighted mean concen t r a t ions

The parameters can be l o o s e l y c l a s s i f i e d i n t o two main groups - t hose a s s o c i a t e d wi th sediment (suspended s o l i d s ) and those which are not .

Suspended s o l i d s flow weighted mean concen t r a t ions w e r e c o r r e l a t e d wi th those of potassium, t o t a l Kjeldahl-, ammonium- and t o t a l n i t r o g e n , t o t a l - and d i s so lved ortho-phosphorus, z inc , l e a d , copper and t h e p e s t i c i d e endosulphan. Nitrate (p lus n i t r i t e ) n i t r o g e n , t o t a l d i s so lved phosphorus, a t r a z i n e and PCB concen t r a t ions were n o t c o r r e l a t e d wi th suspended s o l i d s . Unit a’rea loads of t h e parameters w e r e n o t c o r r e l a t e d t o t h e same e x t e n t as t h e concen t r a t ions . w e l l c o r r e l a t e d w i t h copper, z inc, ammonium- and t o t a l Kjeldahl- n i t rogen and t o t a l phosphorus loads , b u t no t w i th t h e o t h e r parameters which were c o r r e l a t e d wi th suspended s o l i d s as concen t r a t ions .

Suspended s o l i d s loads were

T o t a l K je ldah l n i t r o g e n concen t r a t ions and l o a d s were s t r o n g l y c o r r e l a t e d wi th many o t h e r parameters i n a d d i t i o n t o suspended s o l i d s , i nc lud ing a l l 3 forms of phosphorus, ammonium and potassium, bu t n o t wi th n i t r a t e n i t r o g e n . T o t a l and t o t a l K je ldah l n i t r o g e n concen t r a t ions w e r e c o r r e l a t e d , b u t n o t t h e loads .

A t raz ine w a s c o r r e l a t e d wi th a l l forms of phosphorus as loads , bu t n o t as concen t r a t ions . PCB loads w e r e n e g a t i v e l y c o r r e l a t e d wi th sediment and r e l a t e d parameters, b u t t h e s e c o r r e l a t i o n s d i d n o t appear among t h e flow weighted mean concen t r a t ions .

4 . 2 . 3 R e l a t i o n s h i p s among water q u a l i t y parameters and watershed c h a r a c t e r i s t i c s

4 . 2 . 3 . 1 S i m p l e l inear corre la t i .on

Since many water q u a l i t y parameters were r e l a t e d t o suspended s o l i d s (sediment) , t h i s parameter is d iscussed f i r s t .

Suspended s o l i d s (SS) l oads and flow-weighted mean concen t r a t ions were c o r r e l a t e d s t a t i s t i c a l l y wi th pe rcen t c u l t i v a t e d land, row crops, soybeans and f e r t i l i z e r n i t r o g e n use. Loads of t h i s parameter were , a l s o s t a t i s t i c a l l y n e g a t i v e l y c o r r e l a t e d wi th woodland. of t h e s e r e s u l t s w i l l show t h a t c u l t i v a t e d land and row crop area a r e t h e dominant de te rminants ( s i n c e soybeans were on ly p r e s e n t i n a small number of watersheds) , f e r t i l i z e r n i t r o g e n is a r e f l e c t i o n of c u l t i v a t i o n and row c rops , and woodland is s t r o n g l y a f f e c t e d by c u l t i v a t e d land. Of c u l t i v a t e d land and row crops, t h e former has t h e h igher c o r r e l a t i o n c o e f f i c i e n t s ( r = 0.74 and 0 .71 f o r suspended s o l i d s load and concen t r a t ion r e s p e c t i v e l y ) . These c o r r e l a t i o n c o e f f i c i e n t s are low compared t o those of many of t h e o t h e r parameters. on t h e n a t u r e of t h e sediment y i e l d problem - l a r g e v a r i a b i l i t y between si tes and between seasons, due p r imar i ly t o t h e f low dependency of t h i s parameter .

Examination

Th i s appears t o be a gene ra l r e f l e c t i o n

- 14 -

T o t a l phosphorus (PT) loads and flow-weighted mean concen t r a t ions were both p o s i t i v e l y c o r r e l a t e d on ly with s o i l c l a y content and nega t ive ly w i t h woodland. This la t ter c o r r e l a t i o n sugges t s a farmland in f luence on t o t a l P loads , though n e i t h e r c u l t i v a t e d l and , row c rops , nor any of t h e phosphorus inpu t parameters were s i g n i f i c a n t l y c o r r e l a t e d wi th t o t a l phosphorus loads o r concen t r a t ions . of p o l l u t a n t t r a n s f e r p o t e n t i a l t o s u r f a c e water, which i s h igh ly c o r r e l a t e d wi th s o i l c l a y content . There w a s a l s o a c o r r e l a t i o n observed between t o t a l phosphorus flow-weighted mean concen t r a t ions and soybean acreage - a r e l a t i o n s h i p which is probably due t o t h e c o r r e l a t i o n between suspended s o l i d s and soybeans, and which has a l r e a d y been ques t ioned due t o t h e absence of beans i n many of t h e watersheds s tud ied .

Loads were c o r r e l a t e d wi th t h e index

T o t a l d i s s o l v e d phosphorus (PD) loads and flow-weighted mean concen t r a t ions had similar c o r r e l a t i o n s wi th watershed c h a r a c t e r i s t i c s . The s t r o n g e s t c o r r e l a t i o n s were w i t h s o i l c l a y content and p o l l u t a n t t r a n s f e r p o t e n t i a l t o s u r f a c e waters. Again, as wi th t o t a l phosphorus, nega t ive c o r r e l a t i o n s were seen t o exist wi th woodland. c h a r a c t e r i s t i c s c o r r e l a t e d wi th t o t a l d i s so lved phosphorus were t o t a l watershed area (negat ive) and p e r e n n i a l s t ream d e n s i t y ( p o s i t i v e ) sugges t ing t h a t t h i s parameter is s t r o n g l y in f luenced by s u r f a c e t r a n s p o r t processes . T o t a l d i s so lved phosphorus is, u n f o r t u n a t e l y , a parameter i n which confidence i n 2-year d a t a is l i m i t e d due t o change i n l a b o r a t o r y f i l t e r s i z e a t t h e beginning of 1976.l However, on t h e b a s i s of a c o r r e l a t i o n c o e f f i c i e n t ma t r ix developed f o r March and A p r i l , 1976, concen t r a t ion da ta , t h e same c h a r a c t e r i s t i c s were s i g n i f i c a n t l y c o r r e l a t e d wi th t o t a l d i s so lved phosphorus, as a l s o were r u r a l r e s idences , so t h a t t h e c o r r e l a t i o n s noted above are l i k e l y t o be v a l i d .

Other watershed

Dissolved ortho-phosphorus (PO) loads and flow-weighted mean con- c e n t r a t i o n s were both p o s i t i v e l y c o r r e l a t e d only wi th s o i l c l a y con ten t and p o l l u t a n t t r a n s f e r p o t e n t i a l t o s u r f a c e waters. n e g a t i v e l y c o r r e l a t e d wi th woodland.

They were a l s o

T o t a l Nitrogen (NT) loads and flow-weighted mean concen t r a t ions were c o r r e l a t e d wi th c u l t i v a t e d land, row crops and, more s p e c i f i c a l l y , wi th corn area. They were a l s o c o r r e l a t e d wi th t h e estimate of the t i l e - d r a i n e d area i n each watershed, and n e g a t i v e l y c o r r e l a t e d wi th woodland. Among t h e watershed i n p u t v a r i a b l e s , t o t a l n i t r o g e n w a s c o r r e l a t e d wi th f e r t i l i z e r and f e r t i l i z e r p l u s manure i n p u t s of bo th n i t r o g e n and phosphorus. Nitrogen and phosphorus i n p u t s are c l o s e l y c o r r F l a t e d one wi th t h e o t h e r s o t h a t t h i s apparent anomaly of n i t r o g e n be ing r e l a t e d t o phosphorus i n p u t s is e n t i r e l y t h e r e s u l t of t h i s r e l a t i o n s h i p .

Nitrate (p lus n i t r i t e ) Ni t rogen (NN) l oads and flow-weighted mean concen t r a t ions were r e l a t e d t o watershed c h a r a c t e r i s t i c s i n almost e x a c t l y t h e same way as w a s t o t a l n i t r o g e n descr ibed above. This is t o be expected, however, s i n c e n i t r a t e n i t r o g e n is t h e dominant form found i n t h e watersheds s tud ied . It is worth no t ing t h a t wh i l e n i t r a t e n i t r o g e n and t o t a l n i t r o g e n w e r e s t r o n g l y c o r r e l a t e d wi th both t o t a l n i t rogen i n p u t s ( f e r t i l i z e r p l u s manure) and row c rops , t h e s e two c h a r a c t e r i s t i c s were n o t s i g n i f i c a n t l y c o r r e l a t e d one wi th t h e o the r . However, t o t a l

s h i s change a l s o made a two-year de te rmina t ion of "sediment-phosphorus" impossible.

- 15 .-

nitrogen inputs were strongly correlated with corn area, which was also correlated with total and nitrate nitrogen loads and concentrations. These results suggest that the combination of fertilizer and manure nitrogen inputs is a more significant determinant of nitrogen than intensive cultivation per se. This suggests that mineralization of soil organic N as a resultyf cultivation is less significant as a source of N in water than are the manure and fertilizer inputs.

Total Kjeldahl Nitrogen (NK) was related quite differently to watershed characteristics from nitrate, being strongly affected by sediment yield. The only statistical correlations found were with soil clay content, and negatively with woodland.

Ammonia Nitrogen (AN) loads and concentrations were negatively correlated with watershed area and with woodland. Since these two characteristics were correlated one with the other, but woodland was also correlated with cultivated land, with which ammonia was not correlated, these data suggest that the relationship with area is the most relevant. This may suggest stream or other transport losses and/or transformations.

Potassium (KA) loads and flow-weighted mean concentrations were both correlated with watershed area (negative), stream density and rural residences. This suggests that this parameter is also strongly affected by transmission factors. tanks. Potassium was not correlated with manure or fertilizer inputs.

It may also leach from septic

Heavy metals: Very few characteristics of the watersheds were significantly correlated with heavy metal loads or flow-weighted mean concentrations. Of the three examples used here, copper (CU) loads were not correlated with any characteristic but flow-weighted mean concentrations were correlated with cultivated land (CL) and beans (SY). Since copper was strongly correlated with suspended solids, these correlations can be explained as reflecting sediment concentrations. Zinc (ZN) loads and flow-weighted mean concentrations were correlated with soil clay content (SC). Both zinc and copper concentrations were strongly correlated with total phosphorus (PT) concentrations, and so this apparent effect of clay content appears to be valid. (PB) loads were negatively correlated with watershed slope (AG) and potassium inputs (TN) (fertilizer plus manure); flow-weighted mean concentrations were correlated with soybean area. No explanations exist for these correlations. Lead loads were not correlated with suspended solids but concentrations were. parameters related to suspended solids (e.g. cultivated land) were correlated with lead.

Lead

However, none of the other

Pesticides: Atrazine (AT) and endosulphan (EN) were included in this analysis as representative of currently used herbicides and in- secticides respectively. of atrazine were correlated with soil clay content (SC). Loads were also correlated with pollutant transport potential to surface water (PS), and (negatively) to woodland (WA). correlated with slope (AG). As a parameter, atrazine was strongly correlated only with total Kjeldahl nitrogen (NK), so the influence of clay content on atrazine seems dominant.

Both loads and f low-weighted mean concentrations

Concentrations were negatively

'Pesticides which are no longer used such as DDT were found consistently and were related to sediment. data as the materials are essentially of historical interest only.

However, no analysis was done on these

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It is noticeable that, while corn is the only crop on which atrazine is used, neither loads nor concentrations were significantly correlated with corn area ( C A I . concentrations were correlated with orchards (OR) and vegetables (VA), the crops to which it is most frequently applied. crops were found predominantly in Watershed 1 3 , and so many of the watershed characteristics which had high values in this watershed had significant correlations with endosulphan. Examples were non- agricultural land, rural residences, and fertilizer use. However, the expected incidence of this material in association with its use pattern was confirmed by these results, and the extraneous correlations with the other characteristics can be ignored.

Endosulphan loads and flow-weighted mean

Unfortunately, these

- PCB ( P C ) : This ubiquitous member of the toxic industrial organic contaminants family of compounds was found very consistently in the water draining from the agricultural watersheds. Curiously, while loads of PCB were statistically negatively correlated with those of a number of parameters (e.g. total Kjeldahl N, zinc, potassium, ammonia, dissolved P) , flow-weighted mean concentrations were not correlated with those of any other parameters. Similar inconsistency was seen between loads and flow-weighted mean concentrations and watershed characteristics. The loads were positively correlated with tobacco (TO) and woodland (WA), and negatively correlated with clay (SC) and pollutant transfer potential to surface water (PS). The concentrations were positively correlated with pollutant transfer potential to ground water (PG), row crops ( R C ) , soil extractable phosphorus (SP), fertilizer nitrogen (FM) and fertilizer phosphorus (FP); they were negatively correlated with pasture and hay (PA) and exposed streambanks (ES). There appears to be no reasonable explanation for any of these results, which suggests they are essentially spurious. the concept that PCB inputs to watersheds are by way of atmospheric fallout or spills (there are no other known sources) and that the loss rates of PCB to streams i s not controlled by any factor o r characteristic measured or estimated in these agricultural watersheds.

This fits well with

4.2.3.2 Multiple linear regression analysis:

Each of the water quality parameters discussed so far both as loads and as flow-weighted mean concentrations, were tested with a multiple linear regression package to see if more variability could be explained with combinations of watershed characteristics. To be included in this analysis, the regressions and individual characteristics were only considered if statistically significant at least at the 95% level of probability (p <0.05) .

The resulting regression equations are listed in Tables 1 through Those equations containing variables similar to those which have a 7.

higher r2 value are flagged. transfer to surface water i s often substituted in equations for soil clay co tent - with which it is correlated. lower r desirable equation.

For example, soil potential for pollutant

Whichever equation has the 3 value is flagged as an alternative to the more statistically

A less extensive list of equations is provided in the Tables for This is because this form of data flow-weighted mean concentrations.

- 17 - TABLE 1. Selected Results of Regression of Suspended Solids and Total Phosphorus Unit-Area

Loads and Flow-Weighted Mean Concentrations ~~ ~

No. Var . Para. Units Equation Explained F3

Var. ~ 2 ) -

SS(L)l &/ha 1 1

;A2 3 3

PT(L) kglha 1 1 lA 2 2A 2 2 2 3 3 3

PT(C) mg/L 1 1A 2 2 2 3 3 3

-148 + 8.90CL -762 + 22.46SC + 24.59SP -300 + 7.96SC + 8.46CL 548 - 13.68WA

319.9 - 0.079AR + 16.08CL - 22.54TP 577 - 24.25WA + 23.2SP - 18.43TP 0.13 + 0.029SC 1.22 - 0.026WA 0.35 + 0.84PS -1.08 + 0.047SC + 0.035SP -0.42 + 0.037SC + 0.025FP -0.26 + 0.029Sk + 0.012RC -0.21 + 0.034SC + 0.053RR -0.50 + 0.56SD + 0.016CL -0.65 + 0.043SC + 0.034SP - 0.00007AR -0.95 + 0.037SC - 1.05AU - 0.00013AR -0.63 + 0.015CL + 0.65PS + 0.40SD -13.63 + 3.35RC -0.73 + 3.21FN -331.3 + 8.85SC + 9.,72SP -103.9 + 4.41SC + 3.42E" 91.94 - 0.028AR + 6.48CL - 9.73TP -0.0026 + 0.01SC 0.37 - 0.0089WA -0.53 + 0.018SC + 0.015SP -0.34 + 0.016SC + 0.40PG -0.16 + 0.01OSC + 0.0048RC -0.41 - 0.00002AR + 0.017SC + 0.015SP -0.18 - 0.00004AR + 0.016SC -I- 0.47PG 0.30 + 0.015SC - 0.49AU - 0.000045AR

0.55 0.41 0.75 0.66 0.92 0.85

0.51 0.51 0.42 0.91 0.83 0.80 0.79 0.65 0.99 0.90 0.87

0.43 0.42 0.76 0.64 0.89

0.43 0.41 0.93 0.75 0.75 0.98 0.92 0.91

9.62* 5.56* 10.46** 6.66* 23.01** 11.67**

8.40* 8.40* 5.69* 33.81** 17.34** 13.72** 12.79** 6.57*

249.72** 17.75** 13.81**

6.14* 5.68* 11.18** 6.12* 16.90**

5.92* 5.53* 57.26** 10.61** 10.41** 79.74** 22.89** 19.93**

_ _ ~ ~ ~ ~ ~

'L = unit-area loads C = flow-weighted mean concentrations. For flow-weighted mean concentrations a maximum of

3 cquations, for each of 1, 2 and 3 variables, is included in this table.

equation with higher r2 value. 2A = alternate equation - one or more variables significantly correlated with those of

3F values followed by ** are significant at p 5 0.01 F values f ol lowed by * are significant at p 0.05

- 18 -

expres s ion i s less u s e f u l f o r e x t r a p o l a t i o n purposes than un i t - a rea loads , and because many of t h e r e l a t i o n s h i p s are s imilar t o those presented f o r un i t - a rea loads.

Suspended S o l i d s (sediment) (SS): Both loads and concen t r a t ions of suspended s o l i d s were p o s i t i v e l y r e l a t e d t o s o i l c l a y (SC) and s o i l e x t r a c t a b l e phosphorus (SP) i n m u l t i p l e l i n e a r r eg res s ion (Table 1). When t h r e e v a r i a b l e s were included, watershed area (AR), woodland (WA) and t o t a l phosphorus i n p u t s (TP) presented a nega t ive e f f e c t . The lat ter is unexpla inable , and so t h e th ree -va r i ab le equat ion does n o t seem t o be a s a t i s f a c t o r y improvement over t h e s o i l c l a y (SC) and c u l t i v a t e d land (CL) equa t ion which has v a l i d e x t r a p o l a t i o n p o t e n t i a l .

T o t a l Phosphorus (PT): A cons ide rab le i n c r e a s e i n expla ined v a r i a b i l i t y of t o t a l phosphorus loads was obta ined by combinations of one of several ( c o r r e l a t e d ) parameters t oge the r wi th s o i l c l a y content (SC) (Table 1). presen ted t h e b e s t a d d i t i o n t o s o i l c l a y con ten t f o r bo th load and concen t r a t ions . Considerably poorer were a group of equat ions wi th f e r t i l i z e r phosphorus (FP), row-crops (RC) and r u r a l r e s i d e n c i e s (RR), r e s p e c t i v e l y , i n combination wi th s o i l c l a y content . The r e l a t i o n s h i p which inc ludes f e r t i l i z e r phosphorus is one deserv ing of c l o s e r a t t e n t i o n . It would be tempting t o draw a d i r e c t cause : e f f ec t r e l a t i o n s h i p between phosphorus f e r t i l i z e r u se and t o t a l phosphorus loads. However, t h e problem e x i s t s of determining i f t h e e f f e c t is one of enrichment of runoff wi th phosphorus by f e r t i l i z e r o r one of i nc reased s o i l e r o s i o n s u s c e p t i b i l i t y under row-crops - t h e cropping practice wi th which f e r t i l i z e r i n p u t is c l o s e l y c o r r e l a t e d . Row-crops, however, i s f a r b e t t e r c o r r e l a t e d wi th t o t a l phosphorus loads than is f e r t i l i z e r phosphorus. Furthermore, i f t h e e f f e c t w a s predominantly one of runoff enrichment, then t o t a l phosphorus (which inc ludes manure phosphorus) would be expected t o be a more u s e f u l v a r i a b l e than f e r t i l i z e r phosphorus alone. Th i s w a s n o t t h e case however (un l ike s o l u b l e phosphorus which i s d iscussed below) even though f e r t i l i z e r phosphorus u s e i s c o r r e l a t e d wi th t o t a l phosphorus i n p u t s as w e l l as wi th row-crops. The w e l l e s t a b l i s h e d p r i n c i p l e s of s o i l chemistry a l s o d i c t a t e t h a t most phosphorus added as f e r t i l i z e r w i l l be r e a d i l y sorbed by s o i l p a r t i c l e s , which, i n t h e a g r i c u l t u r a l watersheds, a l r e a d y conta ined up t o 2500 kg/ha i n t h e top 17 cm (from s o i l sample a n a l y s i s - Whitby, MacLean, Schn i l ze r and Gaynor, 1978). The average 2 1 kg/ha/yr of f e r t i l i z e r phosphorus added t o t h e s e watershed s o i l s should, t h e r e f o r e , i n c r e a s e t h e t o t a l s o i l phosphorus content by less than 1%, assuming no crop uptake. For t h i s reason, i t was f e l t t h a t t h e i n c l u s i o n of f e r t i l i z e r phosphorus i n t h i s equa t ion would be mis leading - i t is most l i k e l y t h a t t h i s variable w a s a c t i n g as a s u b s t i t u t e f o r t h e e f f e c t of i n t e n s i v e cropping on s o i l e r o s i o n and sediment movement.

The estimate of s o i l (NaHC03) e x t r a c t a b l e phosphorus (SP)

The o t h e r a l t e r n a t i v e v a r i a b l e l i s t e d i n Table 1 f o r i n c l u s i o n wi th s o i l c l a y con ten t is r u r a l r e s idences (RR). draw a cause :e f f ec t conclus ion regard ing t h i s v a r i a b l e , b u t t h e presence of a h igh d e n s i t y of r u r a l r e s idences i n one watershed wi th s o i l s having h igh s o i l e x t r a c t a b l e phosphorus con ten t s , h igh f e r t i l i z e r i n p u t s and a h igh d e n s i t y of row-crops, sugges t s t h a t t h i s watershed c h a r a c t e r i s t i c is a poor one f o r e x t r a p o l a t i o n purposes. Another com- b i n a t i o n of v a r i a b l e s which w a s s t a t i s t i c a l l y s i g n i f i c a n t i n r e g r e s s i o n of t o t a l phosphorus loadings w a s stream d e n s i t y (SD) and % c u l t i v a t e d l and (a).

It is a l s o tempting t o

- 19 -

The most gene ra l e f f e c t of i n c r e a s i n g t h e number of v a r i a b l e s i n t h e equa t ion from two t o t h r e e w a s t o b r i n g i n t h e nega t ive i n f l u e n c e of watershed area (AR). This is a recognized e f f e c t r e l a t e d t o t h e stream d e l i v e r y - r a t i o concept, b u t is of l i t t l e b e n e f i t i n landscape e x t r a p o l a t i o n . The most a p p r o p r i a t e e x t r a p o l a t i o n equa t ions f o r t o t a l phosphorus loads and flow-weighted mean concen t r a t ions appear t o be those based on s o i l c l a y con ten t (SC) and s o i l e x t r a c t a b l e phosphorus (SP) - t h e la t ter be ing t h e p r e f e r r e d a l t e r n a t i v e t o c u l t i v a t e d land as i t is c o r r e l a t e d w i t h both row-crop l and and f e r t i l i z e r phosphorus use. of s o i l e x t r a c t a b l e phosphorus i s n o t a v a i l a b l e , t h e use of row-crop d e n s i t y i s cons idered t o be t h e b e s t a l t e r n a t i v e .

Where an estimate

T o t a l Dissolved Phosphorus (PD): A s d i scussed earlier i n t h i s r e p o r t , 2-yr. l oad ings of t o t a l d i s so lved phosphorus are n o t r e l i a b l e due t o a change i n l a b o r a t o r y procedures during t h e monitoring per iod. It has t h e r e f o r e been decided t h a t r e g r e s s i o n equat ions w i l l n o t be p re sen ted here . t h e r e g r e s s i o n a n a l y s i s were very similar t o those obta ined f o r d i s so lved ortho-phosphorus, d i scussed below.

Never the less , i t i s worth n o t i n g t h a t t h e r e s u l t s of

Disso lved Ortho-Phosphorus (PO): Loadings of d i s so lved ortho- phosphorus were w e l l accounted f o r by a two-variable r e g r e s s i o n equa t ion which inc luded s o i l c l a y content (SC) and t o t a l phosphorus i n p u t s ( f e r t i l i z e r p l u s manure TP) (Table 2 ) . A l t e r n a t i v e equa t ions included s o i l p o t e n t i a l t o t r a n s f e r p o l l u t a n t s t o s u r f a c e water (PS) and f e r t i l i z e r phosphorus (FP) as s u b s t i t u t e s f o r s o i l c l a y content and t o t a l phosphorus i n p u t s , r e s p e c t i v e l y . Rural r e s i d e n c i e s were a l s o s i g n i f i c a n t i n several 2-var iab le r e g r e s s i o n equat ions. d i s so lved ortho-phosphorus and f e r t i l i z e r phosphorus, t o t a l phosphorus i n p u t s and r u r a l r e s i d e n c i e s compared w i t h t h e r e l a t i o n s h i p s between t h e s e v a r i a b l e s and t o t a l phosphorus is n o t s u r p r i s i n g . The degree of d i s s o c i a t i o n of phosphorus from i ts f i x e d forms t o t h e s o l u b l e s ta te i s known t o be r e l a t e d t o t h e degree of f i x a t i o n by Fey Al, Mn, C a and Mg compounds i n t h e s o i l which, i n t u r n , is somewhat dependant on t i m e as w e l l as s o i l chemical cond i t ions (Brady, 1974) - s o t h e most recent a d d i t i o n s of phosphorus (e.g. by manure o r f e r t i l i z e r ) w i l l be most r e a d i l y desorbed and thus an enrichment i n t h e s o l u t i o n phase may r e s u l t . Thus t h e dominance of t h e inpu t parameters (Fp, MP, TP, RR) over s o i l e r o s i o n f a c t o r s (e.g. pe rcen t row-crops) is n o t s u r p r i s i n g , and appears accep tab le f o r e x t r a p o l a t i o n purposes.

The s t r o n g e r c o r r e l a t i o n s between

A t t h e th ree -va r i ab le level r e g r e s s i o n equa t ion , t h e e f f e c t of dra inage area is n o t as apparent as i t w a s f o r t o t a l phosphorus - presumably because s o l u b l e ortho-phosphorus is n o t as dependant on sediment t r a n s p o r t as i s t o t a l phosphorus. I n s t e a d , combinations of v a r i a b l e s involv ing l i v e s t o c k (All) o r r u r a l r e s i d e n c i e s (RR) wi th f e r t i l i z e r phosphorus (FP) and t o t a l phosphorus (TP), r e s p e c t i v e l y , always wi th s o i l c l a y con ten t (SC), have t h e h i g h e s t r2 va lues (Table 2) f o r loading r e g r e s s i o n s . phosphorus, r u r a l r e s i d e n c i e s (RR) , s o i l c l a y (SC) , and a l t e r n a t i v e s r e l a t e d t o i n t e n s i v e c u l t i v a t i o n (e.g. row-crops, s o i l e x t r a c t a b l e phosphorus) w e r e found a t t h e thxee-var iab le equat ion l e v e l .

For flow-weighted mean concen t r a t ions of d i s so lved ortho-

T o t a l Nitrogen (NT): Mul t ip l e l i n e a r r e g r e s s i o n on t o t a l n i t r o g e n l o a d s i n d i c a t e d a s t r o n g i n f l u e n c e of n i t r o g e n inpu t and c u l t i v a t i o n

- 20 - TABLE 2. Selected Results of Regression of Ortho-Phosphorus Unit-Area Loads and Flow-

Weighted Mean Concentrations

No. Var . Para. Units Equation Explained F3

Var. (r2)

po(L) kg/ha 1 1 1A 2 2A 2 2A 2 2A 2A 2A 3

0.42 - 0.01WA 0.005 + 0.011SC 0.073 + 0.34PS -0.20 + 0.012SC + 0.0084TP -0.17 + 0.013SC + 0.0079FP 0.31 - 0.01WA + 0.14SD

-0.12 + 0.37PS + 0.0084Tp -0.11+ 0.012SC + 0.017RR -0.081 + 0.42PS + 0.0077FP -0.031 + 0.39PS + 0.017RR -0.040 + 0.35PS + 0.003RC -0.20 + 0.012SC + 0.0057TP + 0.01RR

0.68 0.61 0.59 0.90 0.89 0.88 0.88 0.87 0.86 0.85 0.78 0.96

17.34** 12.60** 11.53** 32.50** 29.06** 26.89** 24.89** 23.78** 21.41** 19.62** 12.49** 44.48**

3 3 3 3A 3A 3 3A 3 3A

PO(C) mg/L 1 1 2 2 2 3 3 3

-0.25 + 0.012SC + O.19AU + O.011FP -0.20 + 0.016SC + 0.004RC + 0.016FP -0.19 + 0.36PS + 0.21AU + 0.011FP -0.099 + 0.37PS + 0.017RR + 0.0042CA -0.21 + 0.28PS + 0.004CL + 0.13SD -0.11 + 0.38PS + 0.002CL + 0.014RR

0.056 + 0.37PS + 0.000022AR + 0.0067FP

0.085 + 0.29PS + 0.0029CL - 0.000031AR 0.12 - 0.0031WA -0.006 + 0.0034SC -0.049 + 0.004SC + 0.0067RR -0.068 + 0.0043SC + 0.0028FP -0.12 + 0.0051SC + 0.0034SP -0.10 + 0.0048SC + 0.0046RR + 0.0019SP -0.069 + 0.00057CL + 0.0038SC + 0.0056RR -0,060 + 0.0039SC + 0.0052RR + 0.00061RC

0.95 0.95 0.93 0.93 0.93 0.92 0.92 0.91

0.58 0.55 0.91 0.89 0.86 0.97 0.96 0.95

36.44** 35.20** 26.08** 25.79** 25.37** 22.22** 22.19** 20.61**

11.24** 9.92* 33.88** 27.64** 21.47** 70.09** 47.16** 391 17**

'L = unit-area loads C = flow-weighted mean concentrations. For flow-weighted mean concentrations a maximum of

3 equations, for each of 1, 2 and 3 variables, is included in this table.

equation with higher r2 value. 2A = alternate equation - one or more variables significantly correlated with those of 3F values followed by ** are significant at p 4 0.01 F values followed by * are significant at p 0.05

- 2 1 -

v a r i a b l e s . The h i g h e s t r2 va lues obta ined wi th two v a r i a b l e s included row-crops (RC) t o g e t h e r wi th manure n i t r o g e n (Ill?) and c u l t i v a t e d land (CL) t o g e t h e r w i th t o t a l n i t r o g e n i n p u t (TN) (Table 3 ) . The former i s p r e f e r r e d as i t avoids any problems caused by t h e tendency f o r interdependance of t o t a l n i t r o g e n i n p u t s and c u l t i v a t e d land. Flow-weighted mean con- c e n t r a t i o n s were a l s o inf luenced by watershed area (AR) and t i l e d r a i n d e n s i t y (TD).

L i t t l e improvement i n t h e r e g r e s s i o n occurred by adding a t h i r d v a r i a b l e . T i l e drainage d e n s i t y , a ded t o c u l t i v a t e d land and manure n i t r o g e n i n p u t s gave t h e h i g h e s t r4 va lues f o r l oad ings (Table 3 ) , whi le concen t r a t ions were b e s t descr ibed by exposed streambank (ES) added t o row-crops (RC) and manure n i t r o g e n (MN).

Nitrate ( p l u s n i t r i t e ) Nitrogen (NN): There was a tendency f o r g r e a t e r r e s i d u a l v a r i a b i l i t y wi th n i t r a t e (p lus n i t r i t e ) n i t r o g e n than wi th t o t a l n i t rogen . w e r e included i n t h e r e g r e s s i o n equa t ions , (Table 3 ) , however, and the comments made above f o r t o t a l n i t r o g e n apply equa l ly t o t h e n i t r a t e (p lus n i t r i t e ) parameter.

S i m i l a r v a r i a b l e s t o those s e l e c t e d f o r t o t a l n i t rogen

These r e s u l t s do l i t t l e t o c l a r i f y t h e ques t ion of t h e c o n t r i b u t i o n of minera l ized o rgan ic n i t r o g e n which might be expected t o arise from i n t e n s i v e l y c u l t i v a t e d s o i l s . This is because t h e most i n t e n s i v e l y c u l t i v a t e d s o i l s tend t o have t h e h ighes t f e r t i l i z e r and manure n i t r o g e n inpu t s . Fu r the r r e sea rch w i l l be r e q u i r e d t o determine t h e s i g n i f i c a n c e of t h i s f a c t o r .

T o t a l Kje ldahl Nitrogen (NK): There w a s a s i m i l a r i t y between t h e r e s u l t s f o r t o t a l K je ldah l n i t r o g e n load ings and flow-weighted mean concen t r a t ions and those f o r t o t a l phosphorous. Since Kje ldahl n i t r o g e n inc ludes o rgan ic and ammonium n i t r o g e n , which are a s s o c i a t e d wi th sediment (as is t o t a l phosphorous) t h i s r e s u l t is n o t s u r p r i s i n g . Res idua l v a r i a b i l i t y , however, i s g r e a t e r wi th Kje ldahl n i t r o g e n than wi th t o t a l phosphorous, and few s i g n i f i c a n t t h ree -va r i ab le equat ions w e r e a v a i l a b l e (Table 4 ) .

Ammonium Nitrogen (AN): Both loads and flow-weighted mean concen t r a t ions of ammonium w e r e related t o the combination of s o i l c l a y content (SC) and r u r a l r e s i d e n c i e s (RR) (Table 4 ) . Watershed area (AR), t i l e drainage d e n s i t y (TD) and exposed streambank (ES) a l l seemed t o be e f f e c t i v e a d d i t i o n s t o t h e equa t ions a t the th ree -va r i ab le level, sugges t ing t h a t stream t r a n s p o r t f a c t o r s are important f o r t h i s water q u a l i t y parameter. Rura l r e s i d e n c i e s (RR) are a poor v a r i a b l e because of t h e tendency f o r t h i s v a r i a b l e t o have h igh va lues i n only one watershed. Nevertheless , a l though t h i s same watershed had s o i l s wi th low c l a y con ten t , s o i l c l a y w a s a l s o p o s i t i v e l y r e l a t e d wi th ammonium load and flow-weighted mean concentrat ion. This sugges t s t h a t r u r a l r e s i d e n c i e s may, i n f a c t , be i n f l u e n c i n g ammonium l e v e l s .

Potassium (KA): Regression of potassium loads and flow-weighted mean concen t r a t ions showed many s imilar i t ies wi th ammonium (Tables 4 and 5 ) . Since t h e s e two c a t i o n s behave s i m i l a r l y , i n many r e s p e c t s , i n t h e s o i l , t h i s result tends t o confirm t h e d i s c u s s i o n above f o r ammonium, and suppor t s t h e p r i n c i p l e of r u r a l r e s i d e n c i e s being a p o s s i b l e source of bo th p o l l u t a n t s , - t h e t r a n s p o r t of which i s inf luenced by stream c o n d i t i o n s such as stream d e n s i t y (SD) and exposed streambanks (ES), and by t h e dra inage area (AR).

- 22 - TABLE 3. Selected Results of Regression of Total Nitrogen and Nitrate & Nitrite

Nitrogen Unit-Area Loads and Flow-Weighted Mean Concentrations

No. Para. Units Var. Equation Explained F3 Var. ($1

NT(L) kgfha 1 1A 1A 1 1A 1 lA 2 2 2 2A 2A 2A 2A 2 3

NN(L) kg/ha 1 1A lA 1 lA 1A 2 2 2A 2A

-6.65 + 0.42" 2.65 + 0.72CA 9.89 + 0.18TD 1.77 + 0.29CL 7.25 + 0.30RC 24.84 - 0.47WA 8.94 + 0.27FN -7.73 + 0.47RC + 0.35MN -0.27 + 0.33TN + 0.15CL -4.02 + 0.45TN - 5.19SD -6.31 + 0.34" + 0.13RC -8.16 + 0.49RC + 22.84AU -6.16 + 0.46FN + 0.36MN -10.51 + 0.39CL + 0.27MN 0.91 + 0.41CC + 0.20TD -6.96 + 0.25CL + 0.25MN + 0.11TD -0.20 + 0.66CA -7.46 + 0.36TN 6.46 + 0.16TD -0.55 + 0.26CL 4.11 + 0.27RC 5.65 + 0.24FN -4.15 + 0.40TN - 6.53SD -8.41 + 0.42RC + 0.29MN -6.94 + 0.30MN + 0.40FN -8.03 + 0.42RC + 17.99AU

NT(C) mg/L 1 -0.96 + 0.1OCL 1 -2.17 + 0.12" 2 -3.44 + 0.073CL + 0.073TN 2 2.083 - 4.48PG + 0.15RC 3 -3.33 + 0.16RC + 0.06MN + 13.24ES

NN(C) m g / L 1 1.34 + 0.052TD 1A 0.29 + 0.096RC 1 -2.22 + 0.099TN 2 1.26 - 3.64PG + 0.12RC 3 -0.89 + 0.043CL + 0.03SC + 0.034TD

0.81 0.77 0.65 0.56 0.51 0.46 0.43 0.92 0.92 0.90

0.87 0.84 0.84 0.81 0.95

0. a7

0.75 0.70 0.63 0.51 0.49 0.41 0.86

0.74 0.74

0.82

33.17** 27.01** 14.83** 10.05** 8.26* 6.91* 5.93* 42.97** 37.95** 29.90** 23.64** 22.67**

17.90** 15.17** 36.03**

18. a2**

24.89** 18.28** 13.85** 8.27* 7.58* 5.51* 21.69** 16.22** 10.16** 10.14**

0.75 24.07** 0.67 16.20** 0.94 54.27** 0.92 40.63** 0.97 62.51**

0.80 32.16** 0.76 24.72** 0.66 15.61** 0.93 45.20** 0.93 25.11**

'L = unit-area loads C = flow-weighted mean concentrations. For flow-weighted mean concentrations a maximum of

3 equations, for each of 1, 2 and 3 variables, is included in this table.

equation with higher r2 value. 2A = alternate equation - one or more variables significantly correlated with those of 3F values followed by ** are significant at p 5 0.01

are significant at p s'0.05 F values followed by *

- 23 - TABLE 4. Selected Results of Regression of Total Kjeldahl and Ammonium Nitrogen,

Unit-Area Loads and Flow-Weighted Mean Concentrations.

No. Var . Para. Units Equation

NK(L) kg/ha 1 5.64 - 0.097WA 2 0.25 + 0.30SC - 5.59PS 2 8.49 - 0.32AG - 0.00068AR 3 2.22 - 0.0004AR + 0.28SC - 5.71PS 3 -0.68 + 0.30SC - 5.3PS + 0.15RR

m(L) kg/ha 1 1.67 - 0.00022AR 1 1.18 - 0.029WA 2 -0.43 + 0.035SC + 0.075RR 2 0.75 + 0.55SD - 0.030WA 2A -0.17 + 1.040PS + 0.074RR 3 1.37 - 0.00030AR + 0.021CL - O.Ol1TD 3A 1.80 - 0.00032AR + 0.032RC - 0.018TD 3 -1.40 + 0.018CL + 0.77SD + 6.15ES 3A -1.22 + 0.021RC + 0.71SD + 7.86ES

NK(C) mg/L 1 0.05 + 0.048SC 2 -1.79 + 0.075SC + 0.052SP 3 -0.43 - 0.0002AR + 0.065SC + 1.63PG

0.42 5.86* 0.73 9.44* 0.64 6.24* 0.86 12.46** 0.86 12.25**

0.59 0.43 0.69 0.68 0.62 0.92 0.89 0.85 0.85

11.61** 5.98* 7.96* 7.53* 5.81* 21.62** 15.50** 11.06** 11.02**

0.52 8.56* 0.86 21.54** 0.88 14.03**

m(C) mg/L 1 0.48 - 0.000064AR 0.48 7.31* 1 0.35 - 0.0091WA 0.40 5.39* 2 -0.17 + 0.012SC + 0.026RR 0.76 10.27** 2 -0.12 + 0.012SC + 0.013UA 0.64 6.11* 3 0.041 - 0.000066AR t 0.019SC + 0.38PG 0.89 16.84** 3 -0.72 + 0.016SC + 0.017SP + 1.87ES 0.86 11. go** 3 0.49 - 0.000096AR + 0.011RC - 0.0057TD 0.83 9.49*

'L = unit-area loads C = flow-weighted mean concentrations. For flow-weighted mean concentrations a maximum of

3 equations, for each of 1, 2 and 3 variables, is included in this table.

equation with higher r2 value. 2A = alternate equation - one or more variables significantly correlated with those of 3F values followed by ** are significant at p 5 0.01

are significant at p 3 0.05 F values followed by *

- 24 - TABLE 5. Selected Results of Regression of Potassium and Copper Unit-Area Loads

and Flow-Weighted Mean Concentrations.

No. Var . Para. Units Equation

~~

Explained Var. (r2)

3 P

KA(L) W h a 1 7.88 + 1.097RR 1 23.93 - 0.0025AR 1 5.34 + 9.29SD 2 , -1.70 + 0.39SC + 1.31RR 2A 0.94 + 11.98PS + 1.30RR 2 31.81 - 0.0031AR - 1.18AG 2 10.75 + 9.48SD - 0.33WA 2 -1.49 + 11.037SD + 0.19FN 2A -2.32 + 11.37SD + 0.19RC 2 -0.0016 + 0.00014SC + 0.0045PG 2 -0.0022 + 0.00013SC + 0.00012SP 3 13.85 + 12.40SD - 0.38WA - 0.2OMp 3 13.96 + 12.51SD - 0.38WA - 11.80AU 3 -2.30 + 0.31SC + 3.86SD + 1.15RR 3 -9.38 + 11.31SD + 0.27FN + 61.94ES

cu(L) kg/ha 2 2 3 3 3 3A 3 3A 3 3 3 3 3 3 3 3

0.0039 + 0.0016RR + 0.00096CC 0.00037 + 0.00039CL + O.11ES 0.037 - 0.0000047AR + 0.0012CC - 0.0014MP 0.018 + 0.00057 - 0.00055 + 0.16ES 0.042 - 0.0000049AR + 0.00099CC - 0.023AU 0.028 - 0.0000045AR + 0.0006CL - 0.00024TD 0.022 + 0.018PS - 0.0006PH + 0.17ES 0.005 + 0.00071CL + 0.0027RR - 0.0016FP 0.016 - 0.0000037AR + 0.00092CC + 0.00051SP 0.022 - 0.0000045AR + 0.00094CC + 0.018PG 0.036 - 0.0000039AR + 0.00057CL - 0.00082TP

-0.032 + 0.00088SC + 0.0013SP + 0.15ES

-0.027 + 0.00084SC + 0.044PG + 0.19ES -0.013 + 0.0005SC + 0.0011CC + 0.0021NA -0.0026 + 0.00095FN - 0.003TD + 0.19ES -0.016 + 0.00071SC + 0.00056CC + 0.00084SP

KA(C) mg/L 1 1.72 + 0.41RR 2 -1.78 + 0.14SC + 0.49R.R 2 -1.77 + 3.69SD + 0.080FN 3 -4.26 + 3.78SD + O.1lFN + 19.58ES

0.52 0.48 0.45 0.89 0.86 0.81 0.79 0.74 0.73 0.70 0.63 0.96 0.96 0.95 0.92

0.65 0.64 0.92 0.90 0.85 0.84 0.83 0.81 0.80 0.79 0.79 0.77 0.77 0.74 0.71 0.71

8.69* 7.30* 6.63* 28.46** 21.51** 14.07** 13.22** 10.06** 9.47** 8.32* 5.96* 53.32** 50.98** 35.91** 22.78**

6.43" 6.23* 22.15** 18.57** 11.12** 10.60** 9.71* 8.66* 7.82* 7.63" 7.61* 6.81* 6.68* 5.68* 4.87* 4.82*

0.54 9.39* 0.91 35.45** 0.75 10.23** 0.88 14.42**

CU(C> mg/L 1 0.00081 + 0.00014CL 0.41 5.59* 2 -0.012 + 0.00043SC + 0.00044SP 0.77 11.54** 2 0.0055 - 0.OOOOOlAR + 0.00014CL 0.58 4.77* 3 -0.019 + 0.00044SC + 0.00058SP + 0.0044ES 0.94 33.30** 3 0.010 - O.O000017AR+ 0.00027CL - 0.00041TP 0.84 10.53**

'L = unit-area loads C = flow-weighted mean concentrations. For flow-weighted mean concentrations a maximum of

3 equations, for each of 1, 2 and 3 variables, is included in this table.

equation with higher r2 value. 2A = alternate equation - one or more variables significantly correlated with those of 3F values followed by ** are significant at p 0.01

are significant at p - 0.05 < F values followed by *

- 25 -

Copper (CUI : Table 5 lists a l a r g e number of alternative r e g r e s s i o n equa t ions f o r copper. However, few con ta in combinations of v a r i a b l e s which conform t o e s t a b l i s h e d o r expected cause :e f f ec t r e l a t i o n s h i p s . The appearance of cereal crop area (CC), f o r exam le , i s d i f f i c u l t t o exp la in . One th ree -va r i ab le equa t ion gave high r' va lues f o r bo th load ing and flow-weighted mean concen t r a t ions - this w a s based on s o i l c l a y con ten t (SC), s o i l e x t r a c t a b l e phosphorus (SP) and exposed stream- banks (ES). Since copper w a s c l o s e l y c o r r e l a t e d wi th t h e suspended s o l i d s , t h i s equat ion almost c e r t a i n l y r e f l e c t s t h i s sediment a s s o c i a t i o n .

Lead (PB): Table 6 d i s p l a y s a number of r e g r e s s i o n equa t ions f o r lead. However, i n v e s t i g a t i o n of t h e s e a l t e r n a t i v e s f a i l e d t o reveal c o n s i s t e n t t r e n d s t h a t f i t any reasonable cause : e f f ec t r e l a t i o n s h i p . S ince l e a d w a s n o t used i n any a g r i c u l t u r a l p r a c t i c e s , and was n o t c o r r e l a t e d wi th suspended s o l i d s , t h i s f a i l u r e t o f i n d r e g r e s s i o n equa t ions , which could be a p p l i e d wi th any confidence, is a s a t i s f a c t o r y r e s u l t .

Zinc (ZN): S o i l cl'ay content (SC) i s seen i n Table 6 t o be a c o n s i s t e n t component of many of t h e m u l t i p l e l inear r e g r e s s i o n equa t ions f o r z inc. Other v a r i a b l e s inc luded were s o i l e x t r a c t a b l e phosphorous (SP) , and exposed streambank (ES) . w e r e h i g h l y c o r r e l a t e d wi th sediments (suspended s o l i d s ) , s o t h a t these equa t ions probably r e f l e c t t h i s sediment i n f luence .

Zinc load ings and concen t r a t ions

Endosulfan (EN): Endosulfan loads and flow-weighted mean concen t r a t ions were very unevenly d i s t r i b u t e d among the watersheds, w i th h i g h e s t levels i n watershed #13. v a r i a b l e s which were h igh i n t h i s watershed, wi thout regard t o t h e c a u s e : e f f e c t r e l a t i o n s h i p s . Thus r u r a l r e s idences (RR) and d e g a t i v e animal u n i t s (-AU) appeared t o account f o r as much v a r i a b i l i t y as orchards and vege tab le crops - two of t h e l and u s e s i n which endosulfan is used (Table 7) . vege tab le s , o rcha rds , tobacco) i n t o one v a r i a b l e d i d n o t reduce t h e r e s i d u a l v a r i a b i l i t y . This woul.d, however, be a reasonable approach t o t h e e x t r a p o l a t i o n problem.

This r e s u l t e d i n r e g r e s s i o n s which conta ined many

Combining a l l crops on which t h i s i n s e c t i c i d e is used (Le.

At raz ine (AT): I n s p i t e of t h e f a c t t h a t a t r a z i n e is used on ly on corn, Table 7 shows t h a t i t w a s only a t t h e th ree -va r i ab le r e g r e s s i o n equa t ion l e v e l t h a t corn (CA) is a s i g n i f i c a n t v a r i a b l e . S o i l clay con ten t (SC) and p o t e n t i a l t o t r a n s f e r p o l l u t a n t s t o s u r f a c e water (PS) w e r e more s i g n i f i c a n t i n exp la in ing a t r a z i n e v a r i a b i l i t y than w a s corn area.

- PCB (PC): A s with l e a d , d i scussed above, no reasonable combination of v a r i a b l e s appeared t o account f o r PCB loads and flow-weighted mean concen t r a t ions i n any way which might r e f l e c t l i k e l y cause :e f fec t re- l a t i o n s h i p s . S o i l c l a y con ten t (SC), r u r a l r e s idences (RR) and exposed streambank (ES) a l l showed nega t ive r e l a t i o n s h i p s wi th PCB loads and concen t r a t ions (Table 7 ) . Since PCB, l i k e l e a d , is suspec ted of be ing p r i m a r i l y of atmospheric o r i g i n i n t h e a g r i c u l t u r a l watersheds, i t i s n o t s u r p r i s i n g t h a t t h e s e r e s u l t s w e r e obtained.

4.2.3.3 Non-Linear Regression

An a t t e m p t has been made t o i d e n t i f y any tendency f o r the r e l a t i o n s h i p s d i scussed above t o be non-linear. T h i s w a s done by p l o t t i n g

- 26 - TABLE 6. Selected Results of Regression of Lead and Zinc Unit-Area Loads and

Flow-Weighted Mean Concentrations.

No. Var. Para. Units Equa t ion F3 Explained

Var. (r2)

PB(L) Kg/ha 1 0.018 - 0.00079AG 3 0.016 + 0.0034EP - 0.00089AG - 0.000086TD 3A 0.037 - 0.00024SA - 0.026AU - 0.000074TD 3A 0.036 - 0.00024SA - 0.00026CA - 0.02AU 3A 0.042 - 0.00026SA - 0.00017RC - 0.03AU 3 0.20 + 0.002OEP - 0.0002TP - 0.00088AG 3A 0.026 - 0.0098AU - 0.00026FP - 0.00076AG 3 0.054 - 0.00031PII - 0.001SP - 0.001MP 3 0.039 - 0.00024SA - 0.020AU - 0.00013TN 3 0.031 - 0.00030SA + 0.00026WA - 0.00037MN 3A 0.030 - 0.00026SA + 0.0002WA - 0.022AU 3 -0.0029 + 0.0000022AR + 0.00023SC + 0.0005RR 3 0.034 - 0.00017SA - 0.00025Fp - 0.024AU 3A 0.034 - 0.00018SA - 0.00021TP - 0.02AU

ZN(L) kg /ha 1 0.013 + 0.002SC 3 -0.14 + 0.0036SC + 0.14PG + 0.57ES 3 -0.13 + 0.0035SC + 0.0035SP + 0.41ES 3 0.0041 + 0.0026SC + 0.0013PH + 0.41ES 3A 0.021 + 0.086PS - 0.0015PH + 0 . 4 4 E S 3 -0.086 + 0.0030SC + 0.0015CC + 0.0022SP 3A -0.097 + 0.099PS + 0.0032SP + 0.39ES 3 -0.074 + 0.0024SC + 0.0029CC + 0.0051NA 3A -0.10 + 0.0042SC + 0.0042SP - 0.00094FN 3A -0.077 + 0.091PS + 0,002CC + 0.00022SP 3 0.12 + 0.15PG - 0.0043WA - 0.004FP 3 -0.0097 + 0.0025CL + 0.0089RR - 0.0064FP 3 0.079 - 0.0038WA + 0.0052SP - 0.005FP 3 -0.037 + 0.063PS + 0.004RR + 0.0025CC

PB(C) m g / I , 2 -0.0016 + 0.00014SC t 0.0045PG 2 -0.0022 + 0.00013SC + 0.00012SP

Z S ( C ) ing/T> 2 -0.038 + 0.0014SC + 0.0011SP 2 -0.014 + 0.00029CL + 0.00075SC 3 -0.057 + 0.0014SC + 0.0014SP + 0.12ES 3 -0 .056 + 0.0014SC + 0.055PG + 0.18ES 3 0.037 + 0.066PG - 0.0017WA - 0.0016FP

0.46 0.89 0.85 0.83 0.81 0.79 0.77 0.76 0.74 0.72 0.72 0.72 0.71 0.70

0.43 0.96 0.93 0.78 0.78 0.78 0.78 0.77 0.76 0.75 0.75 0.74 0.73 0.72

6.91* 15.55** 11.29** 9.68* 8.50* 7.45* 6.67* 6.30* 5.66* 5.23* 5.17* 5.16* 4.85* 4.78*

6.11* 48.61** 25.42** 7.27* 7.25* 7.20* 7.02* 6.64* 6.36* 6.09* 5.88* 5.58* 5.35* 5.29*

0.70 8.32* 0.63 5.96*

0.77 11.64"" 0.59 4.98* 0.91 19.10** 0.89 16.69** 0.78 7.29*

'L = unit-area loads C = flow-weighted mean concentrations.

A = alternate equation - one or more variables significantly correlated with those of

For flow-weighted mean concentrations a maximum of 3 equations, for each of 1, 2 and 3 variables, is included in this table.

equation with higher r2 value.

2

< 3F values followed by ** are significant at p - 0.01 F values followed by * are significant a t p 0.05

- 27 - TABLE 7. Selected Results of Regression of Endosulfan Atrazine and Polychorinated

Biphenyls, Unit-Area Loads and Flow-Weighted Mean Concentrations.

No. Var.

Para. Units Equation F3 Explained Var. (r2>

AT(L) kg/ha

EN(C) ua/L

1 1 1 1 2 2 2 2 3 3 3

1 1 1 2 3 3 3

1 1 3 3 3

1 1 1 2 2 7

1

1 1 1 2 3 3 3

0.0041 + 0.0018VA 0.0056 + 0.0130R -0.0036 + 0.0032RR -0.0068 + 0.00054RC 0.014 + 0.010R - 0.019AU 0.012 + 0.0015UA - 0.00027MN -0.00038 + 0.0100R + 0.00024FN 0.0033 - 0.01OSD + 0.0035RR 0.0042 - 0.00055CA + 0.00800R + 0.00048FN 0.0032 + 0.0004OCL + 0.0150R - 0.00089TP 0.0045 + 0.00016CL + 0.010R - O.O0091?fP

-0.0006 + 0.00011SC 0.003 - 0.000072WA 0.000081 + 0.0033PS -0.0012 + 0.0033PS t 0.000024CL -0.0023 + 0.0034PS t 0.00066CA + 0.00000025AR -0.0027 + 0.00000024AR + 0.00011SC + 0.000051CA -0.0002 + 0.0028PS + 0.000054CA - 0.00011AG 0.19 - 0.0025SC 0.17 - 0.077PS 0.22 - 0.0024SC - 0.0031RR - 0.25ES 0.21 - 0.075PS - 0.0031RR - 0.25ES 0.20 - 0.0029SC - 0.0045RR + 0.0006RC -1.48 + 1.036RR -3.003 + 0.41FP -1.93 + 0.98NA -3.35 + 0.75RR + O.11FN -3.56 + 0.83RR + 0.094RC 1.80 + 0.60RR - 0.31CA + 0.12TD -0.089 + 0.029SC 0.018 + 0.00067SP 0.022 + 0.022PG 0.025 + 0.00028FN 0.016 + 0.023PG + 0.00032CA 0.020 + 0.023PG - 0.0005RR + 0.0001TD 0.018 + 0.022PG - 0.0022SD + 0.00030CA 0.02 + 0.024PG - 0.0027RD + 0.00034CA

0.86 0.85 0.81 0.46 0.94 0.94 0.91 0.90 0.98 0.98 0.97

0.73 0.69 0.40 0.83 0.90 0.90 0.87

0.65 0.62 0.97 0.93 0.91

0.80 0.71 0.70 0.91 0.89 0.97

0.64

0.78 0.76 0.59 0.94 0.98 0.96 0.95

48.11** 46.51** 33.30** 6.84* 51.83** 50.85** 35.69** 33.08** 85.28** 84.59** 72.28**

21.86** 17.59** 5.39" 1.7.61** 18.84** 18.13** 13.30**

14.80** 13.04** 7 1.90** 26.42** 2.0.53**

31.413'* 2!0* 02** 18.60** 35.17"" 29.46** 65.19

14.36**

28.95** 24.70** 11.28** 56.39** 96.00** 49.66** 41.43**

'L = unit-area loads C = flow-weighted mean concentrations. For flow-weighted mean concentrations a maximum of

3 equations, for each of 1, 2 and 3 variables, is included in this table.

equation with higher r2 value. 'A = alternate equation - one or more variables significantly correlated with those of

3F values followed by ** are significant: at p 5 0.01 are significant at p 5 0.05 F values followed by *

- 28 -

t h e measured a g a i n s t t h e p r e d i c t e d va lues us ing t h e b e s t l i n e a r r e g r e s s i o n s , and then formula t ing some non- l inear expansions of t h e s e equa t ions i n an a t tempt t o reduce t h e r e s i d u a l v a r i a b i l i t y i n un i t - a rea loads. T i m e d id no t p e r m i t a comprehensive e v a l u a t i o n of t h e many a l t e r n a t i v e s , o r t h e ex tens ion of t h e approach t o flow-weighted mean concen t r a t ions .

The procedure y i e lded worthwhile r e s u l t s on ly f o r suspended s o l i d s , t o t a l phosphorus and n i t r a t e (plus n i t r i t e ) n i t rogen . No s i g n i f i c a n t improvement w a s ob ta ined wi th t h e o t h e r w a t e r q u a l i t y parameters.

Suspended S o l i d s (sediment) (SS): Table 1 shows t h a t s t a t i s t i c a l improvement w a s ob ta ined i n t h e exp lana t ion of suspended s o l i d s u n i t - a-ea loads by t h e a d d i t i o n of c h a r a c t e r i s t i c s i n t o t h e r e g r e s s i o n equat ion which were hard t o exp la in i n a phys ica l sense - e.g. nega t ive e f f e c t of t o t a l phosphorus a d d i t i o n s (TP), and p o s i t i v e e f f e c t of s o i l e x t r a c t a b l e P (SP). Non-linear expansion of t h e “ s o i l c l a y , c u l t i v a t e d land” equat ion d i d n o t y i e l d s t a t i s t i c a l improvement. The simple l i n e a r r e g r e s s i o n on % c u l t i v a t e d land (CL), however, was i n v e s t i g a t e d f u r t h e r and i t w a s found t h a t a n improved equat ion w a s as follows:

ss = 97 + 0.0010 CL’ r2 = 0.70

where SS = suspended s o l i d s u n i t area load ( i n kg /ha /y r ) CL = % of l and area i n c u l t i v a t e d crops

T o t a l Phosphorus (PT): In view of the d i scuss ion of t o t a l phosphorus i n s e c t i o n 4.2.3.2 above, t h e non- l inear r e g r e s s i o n i n v e s t i g a t i o n looked a t t h e combination of s o i l c l ay content (SC) and row-crops (RC) as a way t o o b t a i n a b e t t e r r e l a t i o n s h i p f o r e x t r a p o l a t i o n purposes. a number of non-linear equat ions were considered, t h e fo l lowing equat ion w a s f e l t t o be most appropr i a t e .

2 2

Although

PT = 0.149 + (6.550 SC x + (1.622 RC x r 2 = 0.85

where PT = to ta l phosphorus u n i t area load ( i n kg/ha/yr) SC = s o i l mean c l ay content i n % RC = % of t o t a l area i n row-crops.

Nitrate (plus n i t r i t e ) Nitrogen (NN): A non-linear expansion of t h e most a p p r o p r i a t e e x t r a p o l a t i o n equat ion f o r n i t r a t e (p lus n i t r i t e ) n i t r o g e n seen i n Table 3 w a s found t o be a s l i g h t improvement over t h e l i n e a r ve r s ion . The express ion i s as follows:

2 NN = -1.605 + 0.284X + 0.017X r2 = 0.83

where X = 0.42 RC + 0.29 MN

where NN = n i t r a t e (p lus n i t r i t e ) n i t r o g e n un i t - a rea load ( i n kg/ha/yr) RC = % of t o t a l area i n row-crops MN = n i t r o g e n inpu t s t o s o i l s as manure (kg/ha/yr) .

- 29 -

5.0 EXTRAPOLATION OF RESULTS

The purpose of t h i s s e c t i o n is t o p re sen t an approach t o s e l e c t i o n of s u i t a b l e equa t ions f o r use i n an a t t e m p t t o e x t r a p o l a t e t h e mean annual d a t a ob ta ined i n t h e a g r i c u l t u r a l watershed s t u d i e s t o o t h e r Canadian Great Lakes a g r i c u l t u r a l areas.

5 . 1 C o n s t r a i n t s t o e x t r a p o l a t i o n

C l e a r l y , t h e main c o n s t r a i n t t o t h e use of e x t r a p o l a t i o n procedures is d a t a - both d a t a wi th which t o e x t r a p o l a t e , and d a t a by which t o v e r i f y t h e accuracy (or p l a i n reasonableness) of e x t r a p o l a t i o n a t t e m p t s . C e r t a i n land o r land-use v a r i a b l e s are i n a p p r o p r i a t e f o r e x t r a p o l a t i o n purposes, though they may be u s e f u l de te rminants of water q u a l i t y , i f t h e s e v a r i a b l e s cannot be r e a d i l y measured o u t s i d e a s m a l l area. would be "exposed streambank", " s o i l e x t r a c t a b l e phosphorus", " t i l e d ra inage dens i ty , " etc. Other, more u s e f u l , d a t a may be a v a i l a b l e from such sources as t h e census of a g r i c u l t u r e , s o i l surveys and maps, whi le o t h e r s may be e s t ima ted by apply ing c o e f f i c i e n t s t o one d a t a set t o gene ra t e ano the r , - e.g. manure product ion as a f u n c t i o n of l i v e s t o c k types and numbers.

-

Examples

The c o n s t r a i n t s on t h e a c c e p t a b i l i t y of c h a r a c t e r i s t i c s t o be included i n e x t r a p o l a t i o n f u n c t i o n s can be used as a guide t o equat ion s e l e c t i o n . However, t e s t i n g t h e v a l i d i t y of an e x t r a p o l a t i o n a t t e m p t i s a more d i f f i c u l t problem t o so lve . The ch ie f c o n s t r a i n t f o r a g r i c u l t u r a l purposes is t h a t of ob ta in ing r e l i a b l e stream monitoring d a t a from catchment areas wi th an e n t i r e l y a g r i c u l t u r a l l and use. Most of t h e long-term " h i s t o r i c a l " monitoring network sites i n southern Ontar io w e r e c l e a r l y chosen f o r purposes o t h e r than monitoring a g r i c u l t u r e . Furthermore, many of t h e s e s i t e s have inadequate flow monitoring, accompanying the r o u t i n e sampling, t o permit r e l i a b l e loadings t o be c a l c u l a t e d . The au tho r s searched t h e OMOE h i s t o r i c a l r eco rds and obta ined 97 p o s s i b l e s i tes , of which only n ine could supply loading d a t a wi th s u f f i c i e n t r e l i a b i l i t y t o be inc luded i n t h i s v a l i d a t i o n process . a g r i c u l t u r a l sub-basins of t h e Grand and Saugeen r i v e r s , monitored by PLUARG, t h e r e w e r e 1 4 s i tes (ref 'erred t o as " h i s t o r i c " ) used t o test e x t r a p o l a t i o n as o u t l i n e d i n t h e d i scuss ions which follow.

With f i v e mostly

5.2 E x t r a p o l a t i o n t o t h e Canadian Great Lakes Basin

Suspended s o l i d s (sediment): The equat ions a v a i l a b l e t o d e s c r i b e and p r e d i c t sediment l oads were > o t encouraging. v a r i a n c e were low, even f o r t h e non- l inear equat ion involving c u l t i v a t e d land. When t h i s equa t ion was used t o p r e d i c t t h e sediment loadings i n t h e 14 OMOE " h i s t o r i c " a g r i c u l t u r a l sub-basins, a measured:predicted c o r r e l a t i o n c o e f f i c i e n t of only 0 . 3 4 w a s ob ta ined ( i . e . only 11% of v a r i a b i l i t y i n measured loads accounted f o r by t h e p r e d i c t i o n equa t ion ) . The d i s t r i b u t i o n of the measured and t h e p r e d i c t e d v a l u e s , bo th f o r t h e 10 a g r i c u l t u r a l watersheds and f o r t h e 1 4 OMOE sites is shown i n f i g u r e 2 , t oge the r wi th t h e b e s t - f i t r e g r e s s i o n l i n e s .

Values of expla ined

The poor r e l a t i o n s h i p found i n t h e v e r i f i c a t i o n process f o r suspended s o l i d s sugges ted t h a t i t w a s not: p o s s i b l e t o e x t r a p o l a t e t h i s parameter. No f u r t h e r e x t r a p o l a t i o n s were t h e r e f o r e attempted.

- 30 -

/Oo+

900-

’?\ 800- * % u Q \M 700- .f y

600- %

, d 3

\c,

Jbo-

< qoo-

300-

zoo-

/oo -

x

X

b

X

Fig. 2 Measured and p r e d i c t e d v a l u e s of suspended sediment f o r 10 PLUARG a g r i c u l t u r a l and 1 4 OMOE h i s t o r i c a l s i tes

- 31 -

so t o

' il t a l

T o t a l phosphorus: The second o rde r p r e d i c t i o n equat ion involv ing c l a y conten t and row-crop dens i ty was used t o p r e d i c t loadings of

phosphorus i n t h e 1 4 OMOE sub-basins. These va lues are p l o t t e d on f i g u r e 3, t oge the r w i th t h e loadings obta ined i n t h e 10 a g r i c u l t u r a l watershed sites. F igure 3 i n d i c a t e s t h a t , while t he c o r r e l a t i o n between measured and p r e d i c t e d va lues w a s poor, t h e r e l a t i o n s h i p between t h e p r e d i c t e d va lues and t h e a g r i c u l t u r a l watersheds i n gene ra l w a s good. It can a l s o be seen t h a t t h e equat ion tended t o over -predic t t o t a l phosphorus i n t h e OMOE sub-basins. This is a s a t i s f a c t o r y r e s u l t , as t h e OMOE b a s i n s w e r e a l l l a r g e r than those used i n the a g r i c u l t u r a l s t u d i e s , and were a l l sampled less f r equen t ly . Both of t hese f a c t o r s would tend t o r e s u l t i n lower measured t o t a l phosphorus v a l u e s , except a t very low loads where o t h e r sources such a s s t ream banks and s e p t i c tanks may become s i g n i f i c a n t .

Using t h e equat ion d iscussed above, f i g u r e 4 w a s prepared f o r t h e a g r i c u l t u r a l p o r t i o n of t h e Canadian Great Lakes bas ins . S o i l c l a y con ten t w a s ob ta ined by applying r e p r e s e n t a t i v e va lues t o each of t h e s o i l p o l l u t a n t t r a n s f e r p o t e n t i a l subgroups developed and mapped (Coote, e t a l . , 1974) and e x t r a c t i n g t h e da t a on a watershed b a s i s (Water Survey of Canada System) from t h e Canada Land Inventory computerized Geographic Information System. Row-crop da ta were obtained from t h e 1971 census of a g r i c u l t u r e , e x t r a c t e d and updated as descr ibed on page 8. The d a t a presented i n f i g u r e 4 r ep resen t upstream loadings from r u r a l l and i n gene ra l - t o t h e e x t e n t t h a t such land is r ep resen ted by t h e a g r i c u l t u r a l watersheds, - i n o t h e r words, woodland, highways, streams and households which are normally found in an a g r i c u l t u r a l area are included - but waste d i s p o s a l , urban and ex tens ive f o r e s t l and are no t .

So lub le o r t h o - p h o s p h c E : accounted f o r by m u l t i p l e l i n e a r r eg res s ion . A number of a l t e r n a t i v e p r e d i c t i o n equat ions were a v a i l a b l e , bu t many involved v a r i a b l e s which are d i f f i c u l t t o o b t a i n o r , as i n t h e case of watershed area, d i f f i c u l t t o apply t o a landscape d i s t r i b u t i o n ex t r apo la t ion . equa t ion w a s chosen f o r t e s t i n g :

Soluble ortho-phosphorus loads w e r e w e l l

The fo l lowing

OP (kg/ha/yr) = -0.251 + 0.0117 CL + 0.192 AU + 0.0106 FP

where CL = mean s u r f a c e s c i l c l a y con ten t (x) AU = animal u n i t d e n s i t y (no. /ha) FP = f e r t i l i z e r phosphorus inpu t (kg)

F igure 5 shows t h e d i s t r i b u t i o n of t h e a g r i c u l t u r a l watershed and OMOE sub-basins s o l u b l e ortho-phosphorus load da ta . The c o r r e l a t i o n c o e f f i c i e n t between p red ic t ed and measured loads a t t h e OMOE si tes w a s an accep tab le 0.70. ove res t ima t ion a t h ighe r loads w a s a l s o observed wi th s o l u b l e or tho- phosphorus. t h e s a m e r easons ) , t h e e x t r a p o l a t i o n f o r landscape d i s t r i b u t i o n purposes w a s pursued. Figure 6 p re sen t s t h e e x t r a p o l a t i o n of s o l u b l e or tho- phosphorus t o t h e a g r i c u l t u r a l p a r t of t h e Canadian Great Lakes b a s i n , us ing t h e same d a t a base d iscussed above f o r t o t a l phosphorus.

A s with t o t a l phosphorus, t h e phenomenon of apparent

S ince t h i s was a l s o considered an accep tab le r e s u l t ( f o r

T o t a l n i t rogen : The m u l t i p l e l i n e a r r e g r e s s i o n equa t ion f o r t o t a l n i t r o g e n based on row-crops and manure n i t r o g e n w a s cons idered t o be

- 32 -

X

x

Fig. 3 Measured and p r e d i c t e d values of t o t a l p h o s p h o r u s f o r 10 PLUARG a g r i c u l t u r a l and 1 4 OMOE historical s i t e s

H

0

rt

c P

- 34 -

I

u cn

I

‘ig. 6 Unit-area loads of s o l u b l e ortho-phosphorus from a g r i c u l t u r a l l ands , averaged over a l l r u r a l l and , as est imated wi th a r e g r e s s i o n nodel .

- 36 -

concep tua l ly and s t a t i s t i c a l l y accep tab le f o r p r e d i c t i o n purposes. a p p l i c a t i o n of t h i s equa t ion t o t h e 14 OMOE sub-basins i s shown i n f i g u r e 7. As wi th t o t a l phosphorus, i t can be seen t h a t t h e d i s t r i b u t i o n of t h e d a t a p o i n t s relative t o t h e a g r i c u l t u r a l watersheds is c o n s i s t e n t . Although t h e c o r r e l a t i o n c o e f f i c i e n t f o r t h e measured and p r e d i c t e d t o t a l n i t r o g e n loads a t t h e OMOE sites is also accep tab le (0.681, i n s p e c t i o n of f i g u r e 7 shows t h a t a t low load ings , t h e p r e d i c t i o n equa t ion w a s underes t imat ing t h e load, and i n some cases a c t u a l l y p r e d i c t i n g nega t ive values . A t h igh v a l u e s , however, bo th under and over p r e d i c t i o n occurred. For t h e Canadian b a s i n e x t r a p o l a t i o n , f i g u r e 8 w a s developed from t h e equa t ion shown i n f i g u r e 7 as t h i s seemed t h e most a p p r o p r i a t e , even though t h e v e r i f i c a t i o n r e s u l t s were only of marginal a c c e p t a b i l i t y . Again, t h e source of t h e d a t a used i n t h i s e x t r a p o l a t i o n f i g u r e w a s t h e same as t h a t descr ibed above f o r t o t a l phosphorus.

The

Nitrate (p lus n i t r i t e ) Nitrogen: The b e s t - f i t equa t ion f o r n i t r a t e ( p l u s n i t r i t e ) n i t r o g e n w a s a polynomial mod i f i ca t ion of a r e l a t i o n s h i p similar t o t h a t used above f o r t o t a l n i t r o g e n . The d i s t r i b u t i o n of d a t a i s shown i n f i g u r e 9. The s i t u a t i o n i s similar t o , bu t more s a t i s f a c t o r y than, t h a t d i scussed above f o r t o t a l n i t rogen .

F igure 10 has been developed from t h e equat ion of f i g u r e 9 , and is inc luded h e r e t o r e p r e s e n t what is probably a r e l i a b l e i n d i c a t i o n of t h e d i s t r i b u t i o n of stream n i t r a t e (plus n i t r i t e ) n i t r o g e n loadings t o streams from a g r i c u l t u r e i n t h e Canadian Great Lakes Basins.

Other water q u a l i t y parameters: Other water q u a l i t y parameters f o r which r e g r e s s i o n equat ions were developed were cons idered f o r e x t r a p o l a t i o n purposes. I n a l l cases, however, t h e r e w a s e i t h e r no water q u a l i t y concern (e.g. potassium) o r no d a t a by which t o v e r i f y any e x t r a p o l a t i o n a t tempt (e.g. heavy metals, p e s t i c i d e s ) . It w a s t h e r e f o r e concluded t h a t , f o r the purposes of t h e p re sen t PLUARG e f f o r t , no f u r t h e r e x t r a p o l a t i o n s would be attempted. are a s s o c i a t e d wi th s p e c i f i c c rops , and e x t r a p o l a t i o n of use, r a t h e r than w a t e r q u a l i t y da t a , i s f e a s i b l e and u s e f u l f o r some purposes.

It should be no ted , however, t h a t c e r t a i n p e s t i c i d e s

- 37 -

n "

26

I

X

x /

x

/

x //

- 38 -

0 LL 4 2 0

[I] 'j

rd 0

w <

n

- 39 -

'x

Fig . 9 Measured and p red ic t ed va lues of n i t r a t e & n i t r i t e n i t rogen f o r Lo PLIJARG a g r i c u l t u r a l arid 1 4 OMOE h i s t o r i c a l s i t es

- 40 -

w

Y

J * L

-. 4 1 -

6 . REMEDIAL MEASURES IMPLICATIONS -- The A g r i c u l t u r a l Watershed S tud ie s Overview Analysis was n o t formulated

wi th any expressed o b j e c t i v e of determining remedial measures. However, some p e r t i n e n t comments can be drawn from t h e c o r r e l a t i o n and r eg res s ion r e s u l t s w i th regard t o the p r o b a b i l i t y of c e r t a i n water q u a l i t y parameters responding t o c o n t r o l scena- ' L 10s.

The r o l e of s o i l p a r t i c l e s i z e as a major i n f luence on phosphorus, o rganic n i t r o g e n , z i n c and a t r a z i n e loadings from a g r i c u l t u r a l l and has been c l e a r l y demonstrated. This holds important imp l i ca t ions i n t e r m s of t h e e f f i c a c y of remedial measures s e l e c t e d wi thout regard t o s o i l t e x t u r e . I n c u l t i v a t e d areas, r educ t ion of c u r r e n t loadings may be d i f f i c u l t t o achieve wi th s t anda rd remedial programs because movement of ve ry f i n e s o i l p a r t i c l e s ( t h e most reactive f r a c t i o n ) from the s o i l s u r f a c e t o streams i s o f t e n t h e least c o n t r o l l a b l e by common s o i l e ros ion c o n t r o l p r a c t i c e s such as t iming, sediment catchment b a s i n s etc. Furthermore, l o s s e s of some of t h e s e m a t e r i a l s from f ine - t ex tu red s o i l s may be unavoidable r e g a r d l e s s of t h e land use p r a c t i c e employed.

The in f luence of source m' l te r ia l a v a i l a b i l i t y on stream loadings of t h e more water s o l u b l e contaminants i n streams is evidenced by t h e loadings of s o l u b l e ortho-phosphorus and n i t r a t e n i t rogen which can be accounted f o r t o a cons iderable degree b-q the i n p u t s ( f e r t i l i z e r and manure) of phosphorus and n i t rogen r e s p e c t i v e l y . Endosulfan, an example used h e r e of t h e c u r r e n t l y used p e s t i c i d c s , w a s p re sen t i n r e l a t i o n t o t h e crops on which i t w a s used. Reductions f o r a l l of t hese materials can probably be expected i f i n p u t s a r e redu>:ed, and/or a v a i l a b i l i t y t o t h e water system i s c o n t r o l l e d - e .g . by avoiding con tac t wi th s u r f a c e runof f ; by b e t t e r t iming of n i t rogen a p p l i c a t i o n s t o match crop uptake.

The r e s u l t s i n d i c a t e t h a t some materials, such as PCB and copper , are e s s e n t i a l l y u n r e l a t e d t o any a spec t of a g r i c u l t u r e . r educ t ions should n o t be expected through any remedial programs app l i ed t o a g r i c u l t u r a l a c t i v i t i e s .

Control o r

- 42 -

References

A g r i c u l t u r a l Sub-Committee, 1975; Annual Report 1974-75, A g r i c u l t u r a l Watershed S tud ie s , Can.; Task C A c t . 1, (Can. S e c t . ) , PLUARG, I J C , Windsor, Ont. , pp. 138, A p r i l 1975.

Brady, N.C . , 1974; The Nature and P r o p e r t i e s of S o i l , MacMillan, N.Y. 8 t h Ed., Chap. 17.

Ches t e r s , G . , J .B . Robinson, R. S t e i f e l , T. Bahr, R.C. Os t ry , D.R. Coote and O.M. Whitt , 1978; Task C Summary F i n a l Report; PLUARG, I J C , Windsor, Ont., pp. 66, J u l y 1978.

Coote, D.R., 1975; Data Discuss ion , Water Q u a l i t y Monitoring; ( In) A g r i c u l t u r a l Watershed S tud ie s Annual Report 1974-75, Sec t ion I V Y Task C - Canada, PLUARG, I J C , pp. 138, A p r i l 1975.

Coote, D.R., and R.W. Leuty, 1976a; Routine Monitoring Data Analys is , Unpublished Progress Report. Agric. Canada, O t t a w a , pp. 30, A p r i l 1976.

Coote, D.R. and R.W. Leuty, 1976b; Routine Monitoring of A g r i c u l t u r a l Watersheds - Nut r i en t Data Analys is , Unpublished Progress Report , Ag. Canada, O t t a w a , pp. 24, October 1976.

DeMayo, A. and Emolie Hunt, 1975; NAQUADAT Users Manual, In land Waters D i r e c t o r a t e , Environment Canada, O t t a w a , Ont.

Frank, R. and B.D. Rip ley , 1977; Land Use A c t i v i t i e s i n Eleven A g r i c u l t u r a l Watersheds i n Southern Ontar io , Canada, 1975-76: Report of P r o j e c t 5, A g r i c u l t u r a l Watershed S tud ie s , Task C - Canada, PLUARG, I J C , Windsor, Ontar io , pp. 176, March 1977.

Harris, C.R. , J.R.W. Miles, F.R. Hore and A . J . MacLean, 1973; Report of CDA Task Force f o r Implementation of Great Lakes Water Q u a l i t y Program, Research Branch, Agr i cu l tu re Canada, pp. 170, (Unpublished).

Hai th , D.A. , 1976; Land U s e and Water Qual i ty i n New York Rivers; Jour . Env. Eng. Div., Proc. Am. Soc.. C i r . Engrs. , 102 (EE1):1-15, Feb. 1976.

Hore, R.C. and R.C. Os t ry , 1978a; Grand River Ontar io Summary P i l o t Watershed Report. Ont. Min. of Env. PLUARG, I J C , Windsor, Ont. , pp. 6 3 .

Hore, R.C. and R.C. Os t ry , 1978b; Saugeen River Ontar io Summary P i l o t Watershed Report . Ont. Min. of Env. PLUARG, I J C , Windsor, Ont., pp. 56.

McBean, E.A. and J .E . Gorr ie , 1975; Non-Point Source Con t r ibu t ions t o Water Qua l i ty Problems; Proc. 1 0 t h Can. S p p . , Water P o l l . R e s . Can. Vol. 10. p. 142-150.

Miller, M.H., 1974; The Con t r ibu t ions of P l a n t N u t r i e n t s and P e s t i c i d e s from A g r i c u l t u r a l Lands t o Drainage Water; Dept. of Land R e s . Sc i . , Univ. of Guelph, Unpub. Rep., EPS, Env. Can., pp. 73.

Omernik, J . M . , 1976; The In f luence of Land U s e on Stream Nut r i en t Levels , U.S. EPA, C o r v a l l i s , O r . , EPA-600/3-76-014, pp. 106, Jan. 1976.

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Onta r io Min i s t ry of Agr i cu l tu re and Food, 1972; A g r i c u l t u r a l S ta t i s t ics f o r Ontar io , 1971; Pub. 20.

On ta r io Min i s t ry of Agr i cu l tu re and Food, 1977; A g r i c u l t u r a l S t a t i s t i c s f o r Ontar io , 1976; Pub. 20.

On ta r io Min i s t ry of t h e Environment, 1976; Work Plan; Task C Canadian Sec t ion , Act ivi t ies 1, 3 and 4, PLUARG, I J C , OMOE, Toronto, pp. 47, January 1976.

van V l i e t , L.J.P. , G . J . Wall arid W.T. Dickinson, 1978; Combined F i n a l Report A g r i c u l t u r a l Watershed Study P r o j e c t 16 (Erosional Losses From Agr. Land) and P r o j e c t 17 (Sediment Del ivery Rat ios i n Small A g r i c u l t u r a l Watersheds) Task C A c t . 1 (Can. Sec.) PLUARG, I J C , Windosr, Ont. ( In P r e s s ) .

Whitby, L.M., A . J . MacLean, M. Schn i t ze r and J . D . Gaynor, 1978; Sources, S to rage and Transpor t of Heavy Metals i n A g r i c u l t u r a l Watersheds, F i n a l Report of P r o j e c t 9, A g r i c u l t u r a l Watershed S tud ie s , Task C - Canada, PLUARG, I J C , Windsor, Ont., pp. 142.

- 4 4 -

APPENDIX A

WATERSHED LOCATIONS, CHARACTERISTICS AND WATER QUALITY DATA

(From d a t a of Frank and R ip ley , 1977; and d a t a c o l l e c t e d by On ta r io Min i s t ry of the Environment, Water Resources and Labora to r i e s Branches, and processed by NAQUADAT system i n t o un i t - a rea loads and f low-weighted mean concen t r a t ions . S t a t i s t i ca l program by Engineering and S t a t i s t i c a l Research I n s t i t u t e . )

- 45 -

- 46 -

APPENDIX A -- ABBREVIATIONS USED ON FOLLOWING PAGES

AR CL sc SA EP PS PG SD RR RD RC CA SY TO VA cc PH OR WA NA AU SP FN MN FP MP T N TP AG TD EX FK MK TK ES

WATERSHED CHARACTERISTICS (1975-76)

T o t a l Area of Watershed I n Hectares % Cul t iva t ed Land i n Watershed % of S o i l which i s Clay % of S o i l which i s Sand Erosion P o t e n t i a l - Dimensionless Surface P o l l u t a n t P o t e n t i a l - Dimensionless Ground Water P o l l u t a n t P o t e n t i a l - Dimensionless Pe renn ia l S t r e a m Dens i t i n km/km2

Road Densi ty i n km/km2 % Row Crops % Corn % Soybeans and Whitebeans % Tobacco % Vegetables % Cereals % P a s t u r e and Hay % Orchards % Woods and Unimproved Land % Non A g r i c u l t u r a l Animal Uni t s pe r Hectare S o i l P205 - Dimensionless F e r t i l i . z e r Nitrogen Inpu t kg/ha Manure Nitrogen Input kg/ha F e r t i l i z e r Phosphorus Input kg/ha Manure Phosphorus Inpu t kg/ha T o t a l Nitrogen Inpu t from Manure and F e r t i l i z e r kg/ha T o t a l Phosphorus Inpu t from Manure and F e r t i l i z e r kg/ha Slope - m/km Z T i l e Drained % Exposed Streambank F e r t i l i z e r Potassium kg/ha Manure Potassium kg/ha T o t a l Potassium kg/ha Exposed Streambank as km/km2:

Rural Residences pe r km s

ES = SD X EX 100

WATER QUALITY DATA (1975-77)

EN-L Unit-area Loading of Endosulfan (g/ha/yr) PC-L I' I t 1 1 I' Polychlor ina ted Biphenyls (g /ha /yr )

II 1 1 ' I T o t a l Nitrogen (kg/ha/yr) 1 1 11 T o t a l Kje ldahl Nitrogen (kg/ha/yr) 1 1 'I Suspended S o l i d s (kg/ha/yr) II II

I' Lead (kg/ha /yr )

1 1 I 1 Atraz ine (kg/ha/yr)

'I II I ' N i t r a t e and Ni t r i te Nitrogen (kg/ha/yr)

NT-L '' NK-L ss-L 'I

cu-L I' Copper (kg/ha/yr)

ZN-L 'I 'I Zinc (kg/ha/yr) NN-L 'I

PB-L II 1 1

AT-L I' II 11

- 47 -

KA-L Unit-area Loading of Potassium (kg/ha/yr) AN-L PT-L

1 1 Ammonium Nitrogen (kg/ha/yr) 1 1

1 1 I 1 Total. Phosphorus (kg/ha/yr) PO-L 1 1 I 1 I 1 Ortho-phosphorus (kg/ha/yr)

I 1 I 1 I 1 1 1 T o t a l Kje ldahl N (mg/l) 11 11 1 1 I 1

I t Nit ra te and N i t r i t e N (mg/l) I 1 I 1 I 1 1 1

I t T o t a l N (mg/l) I 1 I 1 I 1 I 1

I ' T o t a l Phosphorus (mg/l) PO-c I 1 I t I 1 1 1 ' I Ortho-phosphorus (mg/l) I 1 1 1 I 1 I 1 Suspended S o l i d s (mg/l)

AN-C Flow-weighted Mean Concentrat ion of Ammonium N (mg/l) NK-C NN-C NT-C PT-C

ss-c EN-C I 1 Endosulfan ( u g / l ) ZN-C Zinc (mg/l) PB-C Lead (mg/l) cu-c KA-c AT-C ' I

PC-c l 1

1 1 1 1 I 1

I 1 I 1 I t 1 1

1 1 I 1 I 1 I 1

I 1 1 1 I 1 I 1 I ' Copper (mg/l)

1 1 1 1 11 II Potassium (mg/l) I 1 I 1 I 1 I 1

I t Atraz ine (mg/l) 11 I 1 I t I 1 Polychlor ina ted Biphenyls ( u g / l )

- 48 -

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APPENDIX B

CORRELATION COEFFICIENT MATRIX

( S t a t i s t i c a l program by Engineering and S t a t i s t i c a l Research I n s t i t u t e , Agr i cu l tu re Canada)

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APPENDIX C

EXTRAPOLATION OF AGRICULTURAL LOADINGS TO E N T I R E GREAT LAKES B A S I N

- 66 -

APPENDIX C

Ex t rapo la t ion of A g r i c u l t u r a l Loadings t o t h e E n t i r e Great Lakes Basin

The PLUARG program had as one of i t s primary o b j e c t i v e s t h e iden-

The material presented i n t h i s appendix w a s p repared f o r t i f i c a t i o n of t h e major p o l l u t a n t gene ra t ing land use areas i n the Great Lakes Basin. t h e Task C Summary Report of t h e Syn thes i s and Ex t rapo la t ion Work Group, as a gene ra l e x t r a p o l a t i o n which could be used by PLUARG.

Since t h e bulk of t h e d a t a c o l l e c t e d i n t h e PLUARG s t u d i e s on t h e e f f e c t of a g r i c u l t u r e has been through t h e Canadian A g r i c u l t u r a l Watersheds S t u d i e s , and s i n c e a g r i c u l t u r e i s t h e most ex tens ive land use i n t h e Lake E r i e Basin it w a s l o g i c a l t h a t t h e r e s u l t s of t hese s t u d i e s should be app l i ed t o t h e Great Lakes Basin as a whole t o a t t empt t o i d e n t i f y those a g r i c u l t u r a l areas wiqh the g r e a t e s t p o t e n t i a l t o gene ra t e Great Lakes p o l l u t a n t s . Before t h i s could b e done, i t w a s necessary t o e s t a b l i s h t h e appropr i a t eness of e x t r a p o l a t i o n equa t ions f o r areas o u t s i d e t h e Canadian Great Lakes Basins .

The most compatible d a t a wi th which t o v e r i f y loading p r e d i c t i o n s f o r t h e Great Lakes Basin, based on t h e PLUARG a g r i c u l t u r a l watershed s t u d i e s , w a s t h a t a v a i l a b l e through o t h e r PLUARG s t u d i e s . Most of t h e sub-basins monitored by PLUARG were, however, of mixed ( r a t h e r than a g r i c u l t u r a l ) l and use. A s ea rch of a v a i l a b l e d a t a i n d i c a t e d 20 p r imar i ly r u r a l sub-basins which appeared s u i t a b l e f o r comparisons of loadings of suspended s o l i d s and t o t a l phosphorus, and 11 f o r t o t a l n i t rogen , provided t h a t adjustments were made f o r t h e c o n t r i b u t i o n s of o t h e r major l and uses . These ad jus tments were made by apply ing mean u n i t area loads f o r urban and f o r e s t e d land i n t h e s e sub-basins and then assuming t h e ba lance of t h e measured load w a s t h e r e s u l t of a g r i c u l t u r a l l and uses . The sub-basins which were used were independent ( loadings do n o t have t o be found by d i f f e r e n c e ) t r i b u t a r y catchments of t h e PLUARG p i l o t water- sheds.

S ince t h e e x t r a p o l a t i o n a t tempt r equ i r ed a base d a t a yea r f o r comparing t h e v a r i a b l e s , t h e ca lendar yea r s 1975 and 1976 were s e l e c t e d f o r t h i s approach. The d a t a presented i n t h e preceeding s e c t i o n s of t h i s r e p o r t , however, were f o r t h e two yea r pe r iod May 1975 t o A p r i l 1977. The equa t ions used i n t h i s s e c t i o n w e r e t h e r e f o r e obta ined from t h e A g r i c u l t u r a l Watershed Study I n t e g r a t o r s who were prepar ing 1976 d a t a e x t r a p o l a t i o n a t t empt s f o r t h e Grand and Saugeen Rivers. below where appropr i a t e .

These sources are r e fe renced

Suspended sediment from r u r a l watersheds

Suspended sediment (suspended s o l i d s ) d a t a were h igh ly v a r i a b l e throughout t h e watershed s t u d i e s . An a t t empt a t e x t r a p o l a t i o n f o r a g r i c u l t u r a l l and based on s imple l i n e a r r e g r e s s i o n on s o i l t e x t u r e and row-crop d e n s i t y , based on t h e r e l a t i v e l y uniform s i z e and stream char- acterist ics of t h e 11 Canadian A g r i c u l t u r a l Watersheds (van V l e i t , Wall and Dickinson, 1978), has been examined. Table C-1 shows these results t o g e t h e r w i th estimates of l oads from urban and f o r e s t e d lands . d a t a f o r t h i s v e r i f i c a t i o n a t tempt were obta ined from t h e pre l iminary Summary P i l o t Watershed Reports of t h e PLUARG s t u d i e s involved, and by pe r sona l communication w i t h p r o j e c t l eade r s .

The

TNj1.E C - 1 COMPARISON OF MEASURED AND PILEDICTED ANNUAL LOADS OF SUSPENDED SEDIMENTS

1 Site ___

GR- 6 GR-13 GR-14 SR-4 SR-5 G- 1 G- 2 G- 3 G-4 G-5 G- 6 G- 7 G- 8 8-23 B-63 3

3

3 3

B- 2 B- 6 MR M- 5 M- 5

Year ~.

1976 1976 1976 1976 1976 19 7 5-76 1975- 76 1975-76 1975-76 19 75-76 197 5-76 197 5-76 197 5- 76 1975 1975 1976 1976 1976 1975-76 1976-77

Total Unit Area Loads (Kg/ha/yr) Stream D i s c h x t 2 Predicted .- load (tonncs/yr)

Urban ___- Forest Men sured __- Predicted (cmlyr) * 6358 1196 14110 4129 0 392 701 1329 511 2 2 4 587 698 6426 668 464 66s 464 623 1773 1773

384 79 5 77 5 333 24 9 25 108 1367 58 701 37 0

6886 0 36 0 36 275 0 0

166 668 304 379 240 101 82 82 20

1 6 5 64 30

1224 0 1 0 1 1 11 11

14 5 69 409 138 191 65 162 655 232 457 189 399 27

3376 5 599 528 64 1 486 44 51

180 33 19 6 73 20 104 165 299 305 129 166 258 154 7 09 702 7 09 702 421 350 3 50

48 42 53 61 59 42 43 43 36 36 63 63 45 29 26 12 10 25 38 11

'GR is Grand River; SR is Saugeen River; G is Gcnessce Rivcr; B is Black Creek; PIR is >Ienomonee River station 463001; M is Mill Creek.

Predicted loads for small, primarily rural, sub-basins using regression of 1976 Canadian Agricultural Watershed unit-area loads o n soil clay content and row crops

2

as follows:

and a representative "best estimate" o f 1090 kglhalyr and 30 kg/ha/yr for urban and Total suspended sediments (kg/ha/yr) = -281+ 13.6(%Clay) + 8.3(9, Row Crops)

forested land respectively.

3The loads for 1975 and 1976 as both years had unusual runoff conditions.

in Black Creek and 75-76 and 76-77 in Plill Creek have been separated

I

rn U

I

- 68 -

The e x t r a p o l a t i o n based on s o i l and row-crop d a t a may be reasonable f o r e s t i m a t i n g i n p u t s from a g r i c u l t u r a l f i e l d s where stream border cond i t ions are similar t o those found i n t h e Canadian Agr i cu l tu re Watersheds. It should be noted t h a t management of l and border ing a stream i s c r i t i c a l t o t h e sediment y i e l d s and may, i n p a r t , account f o r t h e unexplained v a r i a t i o n s seen i n t a b l e C-1. Furthermore, s i n c e t h e p r e d i c t i o n method does n o t i nc lude a flow v a r i a b l e , t h e d iscrepancy found between p r e d i c t e d and measured loads i n t h e Black Creek Watershed can be p a r t l y expla ined by t h e occurrence of a 100 yea r frequency storm i n 1975, and t h e unusual ly low runoff which occurred i n 1976.

It must be concluded t h a t t h i s approach t o e x t r a p o l a t i o n of sediment l oad ings r e q u i r e s f u r t h e r refinement. The sites wi th t h e h i g h e s t p r e d i c t e d loadings w e r e u s u a l l y t h e sites wi th t h e h i g h e s t monitored l o a d s , b u t t h e r e w a s poor agreement i n terms of magnitude of t h e s e loads. D e s p i t e t h i s problem, d i s c u s s i o n wi th PLUARG Task C Synthesis and Ex t rapo la t ion Work Group members i n d i c a t e d a concern f o r t h e i d e n t i f i c a t i o n of t h e h i g h e s t p o t e n t i a l c o n t r i b u t i n g areas, s i n c e suspended s o l i d s (sediment) i s a s i g n i f i c a n t parameter f o r Great Lakes Water Qual i ty . Figure C-1 w a s developed from t h e equa t ion used i n t a b l e C-1. The d a t a f o r t h e Canadian s i d e of t h e b a s i n w e r e ob ta ined i n t h e same way as t h a t desc r ibed i n s e c t i o n 5.2 of t h e main r e p o r t . The s o i l c l a y con ten t d a t a f o r t h e U.S. s i d e w e r e found by u t i l i z i n g t h e s o i l a s s o c i a t i o n maps of t h e U.S. Task B r e p o r t (PLUARG Task B y 1976) and e s t i m a t i n g mean c l a y con ten t s f o r each s o i l series. These mean c l a y con ten t s were obta ined from t h e s o i l c l a y content d e s c r i p t o r inc luded a t t h e s o i l family name l e v e l f o r each s o i l series o b t a i n a b l e from publ i shed l i s t i n g s (SCS, 1977) and applying t h e mean c l ay con ten t l i s t e d f o r d e f i n i t i o n purposes f o r each of t h e s e family names (SCS, 1975). E s t i m a t e s were then made of t h e mean s o i l a s s o c i a t i o n c l a y con ten t by averaging t h e dominant two o r t h r e e s o i l series i n each a s s o c i a t i o n , and applying t h e s e va lues t o t h e e s t ima ted d i s t r i b u t i o n of each a s s o c i a t i o n i n each U.S. Great Lakes County. The county w a s t h e u n i t of area d e s c r i p t i o n used as t h e most d e t a i l e d U.S. census d a t a were a v a i l a b l e only on t h i s b a s i s . d e n s i t y f o r each county w a s ob ta ined from t h e 1976 U.S. census of a g r i c u l t u r e d a t a base (USDC, 1976; Doneth, 1975).

Row-crop

The suspended sediment l oads obta ined from t h e equa t ion of t a b l e C- 1 were weighted according t o t h e percentage of t h e area of each county, o r each sub-basin, i n farm land. The r e s u l t i n g d i s t r i b u t i o n of es t imated a g r i c u l t u r a l l oad ings of suspended sediment is shown i n f i g u r e C-2.

Phosphorus from r u r a l watersheds

The A g r i c u l t u r a l Watershed S tud ie s Phosphorus I n t e g r a t i o n e f f o r t (Miller and S p i r e s , 1978) found t h a t about 85% of t h e v a r i a b i l i t y i n u n i t area loadings of t o t a l P i n 1976 w a s accounted f o r by a second o r d e r equa t ion based on the c l a y con ten t of t h e s o i l and t h e p ropor t ion of land area i n wide space row-crops, - similar t o t h a t d i scussed i n s e c t i o n 5.2 of t h i s r e p o r t . Using this equa t ion t o estimate loadings from a g r i c u l t u r a l l and , t oge the r wi th mean loadings of 2.0 kg/ha/yr and 0.1 kg /ha /y r r e s p e c t i v e l y from urban and f o r e s t e d l and areas, allowed t h e p r e d i c t i o n of t o t a l phosphorus load ings , p re sen ted i n t a b l e C-2, f o r t h e s e l e c t e d sub-basins of t h e PLUARG p i l o t watersheds.

Sediment load to streams over total land area* in kglhalyr

0 0-250

@ 250-500

4, 500-700

>700

I *by county in U.S.; watershed in Canada

Figure C-1 Locations of agricultural land having unit area loads as indicated of suspended sediment

(by extrapolation of 1976 loads to provisional land use data).

- 70 -

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TABLE c-2 COMPARISON OF PLEASURED WITH PREDICTED ANNUAL LOADS OF TOTAL PHOSPHORUS

1 S i t e ___

GR- 6 GR-13 G R - 1 4 SR-4 SR-5 G- 1 G- 2 G- 3 G-4 G- 5 G- 6 G- 7 G-8 B- 2 B- 6 B- 2 B-6 MR M- 5 M-5

3 3 3 3

3

Year -

1976 1976 1976 1976 1976 1975-76 19 7 5- 76 1975-76 1975-76 1975-76 19 7 5-76 1975-76 19 7 5-76 1975 1975 1976 1976 1976 19 7 5- 76 1976-77

AJp-

10.6 12.28 41.39 10.17

2 .84 0.76 1.15 2.35 0.99 0.51 1.04 1.32

11.03 1.67 1.28 1 . 6 7 1.2s 1.25 3.31 3.31

7 Predicted load ( tonnes/yr)L

F o r e s t ~- Urban

0.77 1 .59 1 . 5 5 0.67 0 .5 0.05 0.22 2.73 0.12 1.40 0.08

0 13.77

0 0.08

0 0.08 0.56

0 0

0 . 5 5 2.23 1.01 1 .26 0.80 0.34 0 . 2 7 0.27 0.07 0.55 0.21 0.1 4.08

0 0 0 0 0

0.04 0.04

T o t a l U x i ~ t Area Loads (Kg/ha/yr) Measured P red ic tea

0.3; 0.25 0 . 7 7 0.20 0.28 0.10 0.11 0.44 0.35 0.38 0.30 0 .60 0.15 9-07 6.9 1 .6 1 . 4 2 0.72 0.56 0.33

0.31 0.20 0.57 n . l S

2.23 0.30 0.58 0.61 0.29 0.32 0 .51 0.39 1 . 7 7 1.9 1 . 7 7 1 . 9 0.84 0.66 0.66

0 . 1 7

Stream Discharge J-/YT)

48 42 53 61 59 42 43 43 36 36 63 63 45 29 26 1 2 10 25 36 11

'GR i s Grand River; SR is Saugeen River ; G is s t a t i g n 463001: ?I is ? f i l l C r t e k .

Genesset, Kiver; B i s Black Creek; MK is Menomnet. River

L P r e d i c t e d l o a d s f o r s m a l l , p r i m a r i l y r u r a l , s u b - b a s i n s u s i n g r e g r e s s i o n o f 1 9 7 6 C a n a d i a n A g r i c u l t u r a l W a t e r s h e d u n i t - a r e a l o a d s o n s o i l c l a y c o n t e n t a n d r o w c r o p s a s f o l l o w s : 2

T o t a l p h o s p h o r u s ( k g / h a / y r ) = - 0 . 0 9 4 + O.O0085(X C l a y ) 2 + 0 . 0 0 0 2 1 ( % R o w C r o p s )

a n d a r e p r e s e n t a t i v e " b e s t e s t i m a t e " o f 2 k g / h a / y r a n d 0 . 1 k g / h a / y r f o r u r b a n a n d f o r e s t e d l a n d r e s p e c t i v e l y .

I

P

I

3The l o a d s f o r 1 9 7 5 a n d 1 9 7 6 i n B l a c k C r e e k and f o r 75-76 and 76-77 i n M i l l Creek have been sepa ra t ed as both years had unusual runoff cond i t ions .

- 72 -

I n some cases, the e x t r a p o l a t i o n model does n o t p r e d i c t t h e v a r i a b i l i t y i n t h e measured load e x a c t l y , probably because of t h e h ighe r c l a y conten t of many of t h e U.S. Lake E r i e b a s i n s o i l s compared t o t h e s o i l s of t h e Canadian p a r t of t h e bas in . This n e c e s s i t a t e d e x t r a p o l a t i o n o u t s i d e t h e range of t h e o r i g i n a l a g r i c u l t u r a l d a t a set. The extreme v a r i a b i l i t y i n f low cond i t ions observed i n two yea r s of d a t a a t some of t h e U.S. Task C s tudy s i tes c r e a t e d added d i f f i c u l t i e s . Never the less , t h e uni t -a rea load e x t r a p o l a t i o n procedure does appear t o g ive a n e f f e c t i v e sepa ra t ion of "high" ( g r e a t e r than 1.5 kg /ha /y r ) , "medium" (0.5 t o 1 .5 kg/ha /yr ) and "lowrr (less than 0.5 kg/ha/yr) y i e l d i n g r u r a l areas, d e s p i t e t he l a c k of a f low v a r i a b l e i n t h e equat ion .

The e x t r a p o l a t i o n of t o t a l phosphorus from a g r i c u l t u r a l l and t akes i n t o account a n average e f f e c t of l i v e s t o c k . Modelling procedures i n t h e Canadian A g r i c u l t u r a l Watersheds S tud ie s (Robinson and Draper, 1978) have found t h a t l i v e s t o c k c o n t r i b u t e an average of approximately 0.15 kg of phosphorus pe r animal u n i t pe r yea r . However, s i n c e l i v e s t o c k d e n s i t y w a s n o t a s t a t i s t i c a l l y s i g n i f i c a n t determinant of t o t a l P loading t o t h e streams i n t h e A g r i c u l t u r a l Watersheds s t u d i e d , e x t r a p o l a t i o n of l i v e s t o c k e f f e c t s must be handled as a s e p a r a t e procedure i n o r d e r t o estimate t h e i r probable impact. L ives tock u n i t s and phosphorus product ion i n manure were, however, s t a t i s t i c a l l y s i g n i f i c a n t i n exp la in ing v a r i a b i l i t y i n d i s so lved phosphorus load ings ( see s e c t i o n 4.2.3.2 of t h i s r e p o r t ) . However, s i n c e concen t r a t ions of d i s so lved phosphorus are known t o change markedly dur ing stream t r a n s p o r t , and s i n c e t h e e x t e n t of t h e s e changes cannot be p red ic t ed , e s t ima t ion of lake loadings from upstream i n p u t i s impossible . Ex t r apo la t ion of d i s so lved phosphorus loadings w a s t h e r e f o r e n o t a t tempted.

F igure C-3 shows t h e ex t r apo la t ed loadings of t o t a l phosphorus i n t h e Great Lakes b a s i n from a g r i c u l t u r e based on areas where s o i l s w i th h igh c l a y conten t and predominantly row-crop c u l t u r e occured toge the r . The d a t a sou rces f o r t h i s f i g u r e were t h e same as those f o r f i g u r e C- 1 d i scussed above. These va lues were a l s o weighted by farm-land d e n s i t y , and t h e r e s u l t s shown i n f i g u r e C-4. l i v e s t o c k c o n t r i b u t i o n s t o phosphorus loadings of streams d ra in ing t o t h e Great Lakes. These load va lues should n o t be added t o t h e loads shown on t h e prev ious map, as a v a r i e t y of l i v e s t o c k d e n s i t i e s w e r e p r e s e n t i n t h e base si tes on which t h e f i r s t e x t r a p o l a t i o n of t o t a l phosphorus w a s made. Rather , t he l i v e s t o c k l o a d s should be used t o i n d i c a t e where a c t u a l l oads are probably h ighe r o r lower than those shown by t h e f i r s t e x t r a p o l a t i o n . However, t h e l i v e s t o c k loadings are s m a l l enough t h a t they b r ing about few changes t o t h e expected average a g r i c u l t u r a l loadings.

F igure C-5 shows an e s t ima t ion of

Ni t rogen from r u r a l watersheds

Table C-3 p r e s e n t s t h e r e s u l t s of an e x t r a p o l a t i o n of t o t a l n i t r o g e n loadings from t h e a g r i c u l t u r a l watershed s t u d i e s based on 1976 r e s u l t s (Nei lson, Cul ley and Cameron, 1978). Representa t ive urban and f o r e s t e d land inpu t s of n i t r o g e n used i n t h i s t a b l e w e r e 10 kg/ha /yr and 2 kg lha ly r r e s p e c t i v e l y . S ince n o t a l l PLUARG s t u d i e s have included n i t r o g e n ( t h i s parameter be ing deemed by PLUARG as one of secondary s i g n i f i c a n c e ) , i t w a s n o t p o s s i b l e t o o b t a i n loadings f o r as many r e p r e s e n t a t i v e U . S .

- 73 -

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I Livestock density in animal units/ha and phosphorus l o a d s in kglhalyr

Livestock Density P Loads

n 0-0.165 0-0.033 2-4/55 0.166-0.330 0.034-0.066 418954$8 0.331-0.495 0.067-0.099 D >0.495 >o. 1

I . . ,.

Figure C-5 Livestock density and estimated total phosphorus loads f rom livestock per unit area of all land (by extrapolation to provisional land use data).

TABLE C - 3 COPPARISQN OF MEASURED AND PREDICTED ANNUAL LOADS OF TOTAL NITROGEN

1 S i t e

GR- 6 GR- 13 GR-14 S R - 4 SR-5 B-23 B-23 B-6; 2

B-6' MC-5 MC-5

2 Year Predicted l o a d (tonnes/Yr .> - . --

Urban Fores t __- Agr .

1976 835.7 1976 4 7 4 . 2 1976 1 2 8 4 . 2 1976 717.4 19 76 83.0 1975 11.9 1976 11.9 197: 9.6 1976 9.6 1975-76 61.1 1976-77 61.1

3 . 3 8.0 7.8 3.3 2 . 5

0 0

0.1; 0.4

0 0

11.1 4 4 . 5 20.3 25.3 16 .0 0 c' 2 0 0 0

T o t a l Unit Area Load (Kg/ha/yr) Stream Discharpc _I._____

_____ Pred ic t ed (cm/yr> Measured ____

19.2 5.6 13.1 9.5 6.1 16.3 7.1 9.1 2.4 9 . 7 5.0

2 2 , 1 0 - 6

16 - 9 1 1 . 2

4 .2 12.6 12.6 14 .O 1 4 .0 12.0 1 2 .o

4 8 42. 53 6 I 59 29 l? 26 10 38 11

GR is Grand River; SR is Saugeen River; B is Black Creek; MC is Mill Creek. c

'Predicted loads from small, primarily rural, sub-basins using escl'matrs based on 1976 Canadian Agricultural Watershed data as follows:

Total N (kg/ha/yr) = 0.117(Manure N) + G.O016(Manure N2 4- (Fcrcilizer N x Manure N ) ) 26.0(% corn + potatoes) 4- 3.6(% cereals i- soybeans +vegetables) 0.1(% pasture + hay)

where manure and fertilizer nitrogen are in kg/ha!yr, and a representative "best estimate" of 10 kg/ha/yr and 2 kg/ha/yr for urban and forested land respectively.

3The loads for 1975 and 1976 in Black Creek and 75-76 and 76-77 in Mill Creek have been separated as both years had unusual runoff conditions.

- 77 -

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*

- 78 -

sites as i t w a s f o r suspended s o l i d s and phosphorus. Comparisons of monitored load ings wi th p red ic t ed loadings of n i t r o g e n based on t h i s e x t r a p o l a t i o n shows t h a t t h e r e is a gene ra l , b u t n o t c o n s i s t e n t , tendency f o r p r e d i c t e d v a l u e s to exceed measured va lues by approximately 20%. T h i s ove rp red ic t ion w a s n o t i c e a b l e a t most of t h e U.S. sites. A t t h i s t i m e , no exp lana t ion exists f o r t h e lower loadings of t o t a l n i t rogen measured a t most s i tes compared t o those which might be expected from t h e e x t r a p o l a t i o n procedure, o t h e r than t h e p o t e n t i a l stream t r a n s p o r t l o s s e s t o which n i t r o g e n is s u b j e c t .

F igure C-6 p r e s e n t s t h e r e s u l t of e x t r a p o l a t i n g t h e equat ion and mean va lues used i n Table C-3 t o t h e e n t i r e Great Lakes bas ins . Data sources w e r e t h e U.S. census of a g r i c u l t u r e f o r 1976 and es t imated manure use from Task B (Doneth, 1975)

F igure C-6 serves t o i l l u s t r a t e t h e d i f f e r e n c e between n i t r o g e n loading d i s t r i b u t i o n and t h a t seen f o r phosphorus and suspended s o l i d s . The importance of c rops and l i v e s t o c k , as compared wi th s o i l d i f f e r e n c e s , is ev iden t i n t h i s f i g u r e .

~~ ~~

'The a u t h o r s are indebted t o J . L . B . Cul ley , Land Resource Research I n s t i t u t e , A g r i c u l t u r e Canada, f o r i n t e r p r e t i n g and prepar ing t h e s e d a t a f o r t h e mapping process .

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References

(Appendix C)

Doneth, J . 1975; Materials Usage I n The U.S. Great Lakes Basin. PLUARG Task B (U.S.) I J C , Windsor, Ont. pp. 319, Sept . 1975.

Miller, M.H. and A . C . S p i r e s 19'78; Phosphorus I n t e g r a t i o n Report , A g r i c u l t u r a l Watershed S t u d i e s , Task C (Can. Sec t ion) PLUARG, I J C , Windsor, Ont. pp. 56, March 1978.

Nie lson , G . H . , J . L . B . Cul ley and D.R. Cameron, 1978; Nitrogen I n t e g r a t i o n Report , A g r i c u l t u r a l Watersheds S tud ie s , Task C (Can. Sec t ion) PLUARG, I J C , Windsor, Ont. ( I n P r e s s )

PLUARG Task B (U.S.) 1976; Inventory of Land Use and Land lJse P r a c t i c e s , Vol 's . 1-5, PLUARG, I J C , Windsor, Ont. Apr. 1976.

Robinson, J . B . and D.W. Draper 1978; A Model f o r Es t imat ing Inpu t s t o the Great Lakes from Lives tock E n t e r p r i s e s I n t h e Great Lakes Basin, I n t e g r a t i o n Report , A g r i c u l t u r a l Watershed S tud ie s , Task C (Can. S e c . ) , PLUARG, I J C Windsor, Ont, p p . 29.

S o i l Conservat ion Se rv ice , 1975; S o i l Taxonomy, A g r i c u l t u r a l Handbook Number 436 USDA, SCS.

S o i l Conservat ion Se rv ice , 1977; C l a s s i f i c a t i o n of S o i l S e r i e s of t he United S t a t e s . IJSDA, SCS Aug. 1977.

1J.S. Department of Commerce, 1976; 1974, Census of Agr i cu l tu re , Pre l iminary Report Bureau of The Census, [J.S. D e p t . of Commerce, Wash. D . C . Aug. 1976.

Van V l i e t , L . \ J . P . , G.J. Wall and W.T. Dickinson, 1978; Combined F i n a l Report , A g r i c u l t u r a l Watershed Study P r o j e c t 16 (Eros iona l Losses From Agr i r . Land), and P r o j e c t 17 (Sediment Del ivery Ra t ios i n Small A g r i c u l t u r a l Watersheds, Task C , Canadian Sec t ion ) , PLUARG, I J C , Windsor, O n t . ( i n p r e s s ) .