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Nutrient TrendsNutrient Trendsin the Des Moines in the Des Moines
RiverRiverDonna S. LutzDonna S. Lutz
Des Moines River Water Quality Des Moines River Water Quality NetworkNetwork
What is the Des Moines What is the Des Moines River Water Quality River Water Quality
Network?Network?
• Initiated in July 1967 as preimpoundment study for Saylorville Reservoir, expanded to Red Rock Reservoir in 1971
•Long-term record, 36 years at many sites, total of 182 parameters, nearly 445,000 individual data records
• Currently 7 regular sampling sites, monitored 22 times per year for up to 50 parameters
•Data available through annual reports, paradox database, webpage (soon to be on Iowa STORET)
Des Moines River Basin•Length 350 mi•Width 50 mi•Basin 12,884 sq mi
about ¼ size of IowaSaylorville
Reservoir•24 mi valley/54 mi flood•5,520 acres/ 16,100 flood•1,100 ac-ft/yr sedimentationRed Rock Reservoir•18 mi valley/33 mi flood•15,250 acres/ 1,625,00 fl•4,470 ac-ft/yr sedimentation
Raccoon River Sub-basin
North Raccoon/Middle Raccoon/South RaccoonBasin 3,411 sq mi
Routine ParametersRoutine ParametersRoutine ParametersRoutine Parameters
PhysicalPhysical temperature, flow/elevationtemperature, flow/elevation turbidity, secchi disc depth, gas saturationturbidity, secchi disc depth, gas saturation
ChemicalChemical dissolved oxygen, BOD, TOC, nutrients, dissolved oxygen, BOD, TOC, nutrients,
suspended solidssuspended solids metals, pesticidesmetals, pesticides
BiologicalBiological chlorophyll pigmentschlorophyll pigments bacteriabacteria
Long termLong term historical recordhistorical record
what is normal?what is normal?
trend analysistrend analysis any improvement?any improvement?
suspended solidssuspended solids nutrient nutrient
ammonia, nitrate, ammonia, nitrate, phosphatephosphate
pesticidespesticides chlorophyll pigmentschlorophyll pigments
Important ProgramsImportant Programs Short termShort term
bacteria at beachesbacteria at beaches safe to swim?safe to swim?
pesticides in fishpesticides in fish safe to eat?safe to eat?
total gas saturationtotal gas saturation safe for fish?safe for fish?
overall monitoringoverall monitoring why? what’s up?why? what’s up?
Significant FindingsSignificant FindingsSignificant FindingsSignificant Findings
Non-point sources are the main Non-point sources are the main contaminantscontaminants;; soil erosion and siltation primary resource problemsoil erosion and siltation primary resource problem
Ave. loading to Red Rock 5,400 metric tons/dayAve. loading to Red Rock 5,400 metric tons/day
Point source loading has decreasedPoint source loading has decreased Improved wastewater treatment has significantly Improved wastewater treatment has significantly
reduced ammonia loadingreduced ammonia loading
Nitrate levels increased until 1982Nitrate levels increased until 1982, , no no current trendcurrent trend
Total Phosphate levels have decreased Total Phosphate levels have decreased slightlyslightly, , but only by about 0.01 mg/yearbut only by about 0.01 mg/year
Significant Findings Significant Findings (cont’d)(cont’d)
Overall, Overall, water quality has significantly water quality has significantly improvedimproved at most sites, at most sites, according to water according to water quality index valuesquality index values
Pesticide levels in fish are lowPesticide levels in fish are low, , but may still but may still be of concernbe of concern
Gas supersaturation-induced gas Gas supersaturation-induced gas bubble traumabubble trauma causes periodic fish kills below causes periodic fish kills below Red Rock DamRed Rock Dam
Nutrient TrendsNutrient Trends Total NitrogenTotal Nitrogen
Nitrogen FormsNitrogen Forms NitrateNitrate AmmoniaAmmonia Nutrient criteria – total nitrogen (rivers)Nutrient criteria – total nitrogen (rivers)
Total PhosphorusTotal Phosphorus OrthophosphateOrthophosphate Nutrient criteria – total phosphorus Nutrient criteria – total phosphorus
(rivers)(rivers) Phosphorus in sedimentPhosphorus in sediment
Importance of River FlowImportance of River Flow
Low FlowLow Flow Nutrients can decrease due to algal Nutrients can decrease due to algal
utilizationutilization However, nutrients may increase if there However, nutrients may increase if there
are point sources due to lack of dilutionare point sources due to lack of dilution High FlowHigh Flow
Nutrients, especially nitrate and total Nutrients, especially nitrate and total phosphate may increase with storm eventsphosphate may increase with storm events
Antecedent precipitation importantAntecedent precipitation important
Algal UtilizationAlgal Utilizationof nutrients under low flowof nutrients under low flow
Temp C
Flowcfs
Chl a mg/m3
NH4mg/l
NO3 mg/l
T PO4mg/l
O PO4mg/l
7/22/2003 22.9 3240 73 0.03 11.0 0.64 0.25
8/5/2003 24.4 856 162 0.01 3.52 0.55 <0.03
Nitrogen Inputs
Fertilizer25%
Legumes20%
Wet Deposition9%
Soil N26%
Manure13%
Dry Deposition7% Industry
<1%Human<1%
Estimated Point and Non-Point Source Contributions to Stream N-Load
Point Source8%
Non-Point Source
92%
Total NTotal N1967-761967-76
100100
Organic NOrganic N 1414
Ammonia Ammonia NN 77
NO2+NO3 NO2+NO3 NN 7979
2000-2000-0303
100100
2121
11
7878
Nitrogen Forms, %
Above Saylorville Reservoir (St. 1)
Below Saylorville Reservoir (St.5)
1977-1977-8181
100100
1616
44
8080
Total NTotal N1967-761967-76
100100
Organic NOrganic N 1616
Ammonia NAmmonia N 66
NO2+NO3 NO2+NO3 NN 7878
1977-1977-8181
100100
1515
77
7878
2000-2000-0303
100100
1313
22
8585
Nitrogen Forms Raccoon River near Van Meter
12%
15%
84%
84%
4%
1%
Organic N
Ammonia N
NO2+NO3 N
Total N monthly mean1972-81 7.45 mg/l2000-03 8.55 mg/l
1972-81
2000-03
Total NTotal N1967-761967-76
5.865.86
Organic NOrganic N 0.840.84
Ammonia Ammonia NN 0.400.40
NO2+NO3 NO2+NO3 NN 4.624.62
2000-2000-0303
7.897.89
1.631.63
0.060.06
6.206.20
Nitrogen Forms, Concentration
Above Saylorville Reservoir (St. 1)
Below Saylorville Reservoir (St.5)
1977-1977-8181
8.258.25
1.301.30
0.300.30
6.656.65
0
2
4
6
8
10
Tot N Org N Amm NO3
1967-76 1977-81 2000-03
0
2
4
6
8
10
Tot N Org N Amm NO3
1967-76 1977-81 2000-03
Total NTotal N1967-761967-76
5.675.67
Organic NOrganic N 0.890.89
Ammonia NAmmonia N 0.320.32
NO2+NO3 NO2+NO3 NN 4.464.46
1977-1977-8181
6.556.55
0.990.99
0.430.43
5.135.13
2000-2000-0303
7.257.25
0.970.97
0.150.15
6.136.13
Nitrite +Nitrate NNitrite +Nitrate N Ammonia oxidized to nitrateAmmonia oxidized to nitrate (bacterially (bacterially
mediated)mediated) Nitrite, intermediate product, (1967-76, max Nitrite, intermediate product, (1967-76, max
0.68 mg/l, 99% of samples <0.20 mg/l)0.68 mg/l, 99% of samples <0.20 mg/l) SourcesSources
Fertilizers, oxidation or organic N, fixation of Fertilizers, oxidation or organic N, fixation of NN22, precipitation, sewage effluents, precipitation, sewage effluents
LossesLosses Leaching, assimilation living organisms, Leaching, assimilation living organisms,
conversion to other formsconversion to other forms Soluble, easily leaches from soilSoluble, easily leaches from soil
Nitrate vs Flow Des Moines River near Boone
0
2
4
6
8
10
12
1968
1970
1972
1974
1976
1978
1980
1982
1984
1986
1988
1990
1992
1994
1996
1998
2000
2002
Nitra
te m
g/l
0
2000
4000
6000
8000
10000
12000
Flow
(cfs
)
Flow Nitrate
Nitrate vs Flow Raccoon River near Van Meter
0
2
4
6
8
10
12
1973
1975
1977
1979
1981
1983
1985
1987
1989
1991
1993
1995
1997
1999
2001
2003
Nitra
te m
g/l
0
2000
4000
6000
8000
10000
12000
Flow
(cfs
)
Flow Nitrate
Nitrate vs FlowDes Moines River near Boone
R2 = 0.63
0
1
2
3
4
5
6
7
8
9
10
0 2000 4000 6000 8000 10000 12000
Flow (cfs)
Nitra
te (m
g/l)
Seasonality of Nitrate Concentrations
Spring Summer FallWinter
Raccoon River, monthly means unadjusted
Seasonality of Nitrate Concentrations
Spring Summer FallWinter
Raccoon River, monthly means flow adjusted
Seasonal Kendall Tau Trend Analysis, Significant Trends (95%)(from Monthly Mean Data, flow-adjusted)
Des Moines River near Boone NO2+NO3 N 1967-2003 1967-1982 1983-2003 n 438 186 252 mean 5.70 5.27 6.00 slope no trend + 0.23 no trend Raccoon River near Van Meter NO2+NO3 N 1972-2003 1972-1982 1982-2000 n 377 125 252 mean 7.00 6.55 7.22 slope no trend + 0.36 no trend
NO2+NO3 N
Exceedance vs Flow Des Moines River near Boone
0
1
2
3
4
5
6
7
8
9
1968
1970
1972
1974
1976
1978
1980
1982
1984
1986
1988
1990
1992
1994
1996
1998
2000
2002
# of
mon
ths
>10
mg/
l Nitr
ate
0
2000
4000
6000
8000
10000
12000
Flow
(cfs
)
months Flow Linear (months)
Exceedance vs FlowRaccoon River near Van Meter
0
1
2
3
4
5
6
7
8
9
1973
1975
1977
1979
1981
1983
1985
1987
1989
1991
1993
1995
1997
1999
2001
2003
# of
mon
ths
>10
mg/
l Nitr
ate
0
1000
2000
3000
4000
5000
6000
Flow
(cfs
)
months Flow Linear (months)
1968
1971
1974
1977
1980
1983
1986
1989
1992
1995
1998
2001
0
2
4
6
8
10
12Ni
trate
mg/
l
Nitrate Concentration
Des Moines River Raccoon River
196819711974
1977
1980
1983
1986
1989
1992
1995
1998
2001
0
20
40
60
80
100
120
140
160Ni
trate
Tra
nspo
rt (1
,000
kg/
day)
Nitrate Transport
Raccoon River Des Moines River
Nutrient CriteriaNutrient CriteriaT N in rivers 2.62 mg/lT N in rivers 2.62 mg/l
DMR Boone
DMR Sayl
Rac R Van
MeterDMR DM
DMR Runnells
DMR Pella
ave 7.89 7.25 8.52 8.38 8.19 6.45
min 1.36 1.41 1.24 3.00 3.46 1.40
max 17.0 14.4 17.7 15.3 14.6 11.4
#months <2.62 9 5 4 0 0 2
n 44 44 44 44 44 44
% 20 11 9 0 0 5
Data from 5/2000-03
Stations
1 5 10 6 7a 9
Water Year Mean
Discharge (cfs) 3,192 3,428 2,085 6,064 7,662 7,525
Suspended solids(1,000 kg/day)
1,623 389 3,328 3,932 5,027 600
Ammonia N (kg/day)
1,084 1,497 915 3,256 3,156 3,669
Nitrate (kg/day) 66,000 67,000 46,000 125,000 145,000 125,000
Total phosphate 6,722 4,422 8,351 17,679 – 9,709
Transport of Nutrients and Effects of Reservoirs
Stream Flow Separation Stream Flow Separation and Nitrate Nitrogenand Nitrate Nitrogen
Hydrograph separation using USGS program Hydrograph separation using USGS program HYSEP (Sloto and Crouse, 1996)HYSEP (Sloto and Crouse, 1996)
Regression analyses determined if annual Q vs P Regression analyses determined if annual Q vs P relationship changed over timerelationship changed over time
Regression analyses of annual P, Q, Qb, Qs, and Regression analyses of annual P, Q, Qb, Qs, and Q% over time Q% over time
Nitrate data summarized into monthly meansNitrate data summarized into monthly means Regression and correlation of monthly mean Regression and correlation of monthly mean
nitrate to streamflow componentsnitrate to streamflow components
(Schilling and Lutz)
1900 1920 1940 1960 1980 2000
Tot
al D
isch
arge
(in
)
0
5
10
15
20
25
1900 1920 1940 1960 1980 2000
Bas
eflo
w D
isch
arge
(in
)
0
5
10
15
1900 1920 1940 1960 1980 2000
Sto
rmflo
w D
isch
arge
(in
)
0
5
10
15
1900 1920 1940 1960 1980 2000
Bas
eflo
w P
erce
ntag
e
20
30
40
50
60
70
80
Results – Streamflow Results – Streamflow ChangesChanges
Streamflow Changes, Streamflow Changes, cont.cont.
Annual precipitation also increased Annual precipitation also increased during 1916-2000 periodduring 1916-2000 period
Regression residuals indicate change Regression residuals indicate change in rainfall-runoff relationship since in rainfall-runoff relationship since 1916 (p<0.05)1916 (p<0.05)
Thus, more precipitation is being Thus, more precipitation is being routed into streamflow as baseflow routed into streamflow as baseflow in latter portion of 20in latter portion of 20thth century century
Regression Models Regression Models Relating Baseflow to Relating Baseflow to
NitrateNitrateAnnual NO3-N Conc. Versus Baseflow Discharge (in)
y = 0.6202x + 3.9537
R2 = 0.6098
0
2
4
6
8
10
12
14
0 2 4 6 8 10 12 14
Discharge (in)
Me
an
An
nu
al N
O3
-N C
on
ce
ntr
ati
on
(m
g/l)
Qb provided best r2 value (0.61) compared to Q (0.59), Qs (0.48) or Q% (0.27)
HistoricHistoricalal
PerspecPerspectivetive What role What role
might might changing changing streamflow streamflow hydrology in hydrology in the Raccoon the Raccoon River have had River have had on nitrate on nitrate concentrationsconcentrations??
Log Mean Monthly Qb
1 2 3 4 5
NO
3-N
Con
cent
ratio
n (m
g/l)
0
2
4
6
8
10
12
14
16
1945-461972-2000
Log Mean Annual Qb
1 2 3 4 5
NO
3-N
Con
cent
ratio
n (m
g/l)
0
2
4
6
8
10
12
WY1946
1972-2000
Ammonia NAmmonia N
SourcesSources Biological degradation of organic matterBiological degradation of organic matter Point source - wastewater effluentPoint source - wastewater effluent Nonpoint sources - fertilizer, feedlotsNonpoint sources - fertilizer, feedlots
ImportanceImportance Oxidation of ammonia exerts an oxygen Oxidation of ammonia exerts an oxygen
demanddemand Unionized ammonia form toxic to Unionized ammonia form toxic to
aquatic lifeaquatic life
Point Source Event 1977Point Source Event 1977
0
5
10
15
20
25
Am
mon
ia m
g/l
0
50
100
150
200
250
300
350
400
Flow
cfs
Ammonia Flow
Fish Kill Event
Point Source Event 1977Point Source Event 1977
0
2
4
6
8
10
12
14
16
18
Tem
pera
ture
C
0
50
100
150
200
250
300
350
400
Flow
cfs
Temperature Flow
Fish Kill Event
0
1
2
3
4
5
6
7
8
Tot P
hosp
horu
s m
g/l
0
50
100
150
200
250
300
350
400
Flow
cfs
Total Phosphorus Flow
Fish Kill Event
Point Source Event 1977Point Source Event 1977
Ammonia N Ammonia N DMR below DMDMR below DM
0
2
4
6
8
10
12
14
16
18
Jul-71 Jul-74 Jul-77 Jul-80 Jul-83 Jul-86 Jul-89 Jul-92 Jul-95 Jul-98 Jul-01
Am
mon
ia N
(mg/
l)
1
10
100
1000
10000
100000
Flow
(cfs
)
Ammonia N Flow
Unionized AmmoniaUnionized Ammonia
Unionized Ammonia
DMR near
Boone
R River near Van
Meter
DMR below Des
Moines
DMR near
Boone
R River near Van
Meter
DMR below Des
Moines
Date1967-2003
1972-2003
1971-2003
1999-2003
1972-2003
1999-2003
No. months 439 378 391 60 60 60
mean 0.009 0.006 0.015 0.002 0.004 0.004
Min <0.001 <0.001 <0.001 <0.001 <0.001 <0.001
Max 0.267 0.093 0.373 0.013 0.040 0.026
%<0.016 13% 7% 27% 0% 3% 2%
PhosphorusPhosphorus
Major sources Major sources Nonpoint - fertilizers associated with Nonpoint - fertilizers associated with
sedimentsediment Point – wastewater & food processing Point – wastewater & food processing
plant effluents plant effluents Importance Importance
Limiting nutrient (when N:P ratio >16:1)Limiting nutrient (when N:P ratio >16:1) Can be re-suspended or released from Can be re-suspended or released from
sedimentssediments
Phosphorus Inputs
Fertilizer54%
Manure45%
Industry<1%
Human1%
Estimated Point versus Non-Point Contributions to Stream P-Load
Point Source20%
Non-Point Source
80%
Total Phosphate Des Moines River below DM
0
2
4
6
8
10
12
14
16
18
20
Ju
l-7
1
Ju
l-7
3
Ju
l-7
5
Ju
l-7
7
Ju
l-7
9
Ju
l-8
1
Ju
l-8
3
Ju
l-8
5
Ju
l-8
7
Ju
l-8
9
Ju
l-9
1
Ju
l-9
3
Ju
l-9
5
Ju
l-9
7
Ju
l-9
9
Ju
l-0
1
Ju
l-0
3
To
tal
Ph
os
ph
ate
mg
/l
1
10
100
1000
10000
100000
Flo
w c
fs
TPO4 Flow (cfs)
Total Phosphate Des Moines River near Boone
0
2
4
6
8
10
12
14
16
18
20F
eb
-71
Fe
b-7
4
Fe
b-7
7
Fe
b-8
0
Fe
b-8
3
Fe
b-8
6
Fe
b-8
9
Fe
b-9
2
Fe
b-9
5
Fe
b-9
8
Fe
b-0
1
To
tal P
ho
sp
hate
mg
/l
1
10
100
1000
10000
100000
Flo
w c
fs
TPO4 Flow (cfs)
Seasonal Kendall Tau Trend Analysis, Significant Trends (95%) (from Monthly Mean Data, flow adjusted)
Des Moines River near Boone Tot Phosphate 1971-2003 1971-1986 1999-2003 n 188 129 59 mean 0.93 1.07 0.62 slope -0.013 no trend -0.054 Raccoon River near Van Meter Tot Phosphate 1972-2003 1972-1986 1999-2003 n 194 135 59 mean 1.10 1.17 0.94 slope -0.004 0.017 no trend Des Moines River below Des Moines Tot Phosphate 1971-2003 1971-1986 1999-2003 n 207 148 59 mean 1.98 2.15 1.57 slope -0.018 -0.038 no trend
Total Phosphate
1999-03 Phosphorus1999-03 Phosphorus
DMR Boone
DMRSayl
RR Van
MeterDMR
DMDMR
RunnellsDMR Pella
O P
ave 0.05 0.10 0.11 0.46 0.47 0.18
min 0.01 0.01 0.01 0.10 0.11 0.04
max 0.39 0.40 0.49 2.08 1.19 0.45
T P
ave 0.21 0.13 0.29 0.51 0.59 0.24
min 0.04 0.03 0.05 0.21 0.17 0.10
max 0.56 0.43 1.19 1.55 1.34 1.16
% O P 26 72 36 90 78 78
Nutrient CriteriaNutrient CriteriaT P in rivers 0.118 mg/lT P in rivers 0.118 mg/l
DMR Boone
DMR Sayl
Rac R Van
MeterDMR DM
DMR Runnells
DMR Pella
ave 0.21 0.13 0.29 0.51 0.59 0.24
min 0.04 0.03 0.05 0.21 0.17 0.10
max 0.56 0.43 1.19 1.55 1.34 1.16
#months <0.118 8 4 6 0 0 1
n 59 59 59 59 59 59
% 14 7 10 0 0 2
Data from 1999-03
Total PhosphorusTotal PhosphorusSaylorville Saylorville Reservoir Reservoir SedimentsSediments
aveaveDepthDepth (cm)(cm)
Water Content Water Content (%)(%)
Dry Bulk Dry Bulk Density Density (g/cm(g/cm33)) TP (mg/kg)TP (mg/kg)
HeadHead 88 241241 0.330.33 946946
HeadHead 2626 190190 0.380.38 817817
DamDam 1212 304304 0.280.28 12321232
DamDam 22 22 220220 0.350.35 10191019
DamDam 46 46 198198 0.370.37 920920
Cheney Reservoir, Kansas, USGS, Dam 647 mg/kg, Headwaters 477 mg/kg
If interested contact me about statistical methods employed or see notesfrom this slide
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