Lake Decatur Watershed 15-year Monitoring: Nitrates and Trendsilrdss.isws.illinois.edu/pubs/govconf2011/session3c/Keefer.pdf · Lake Decatur Watershed 15-year Monitoring: Nitrates

Lake Decatur Watershed

15-year Monitoring:

Nitrates and Trends

Laura L. Keefer, Erin Bauer & Momcilo MarkusIllinois State Water Survey

Prairie Research Institute

University of Illinois

Champaign, Illinois

• City of Decatur, Keith Alexander

• ISWS Staff

Acknowledgements

Field staff Data processing Lab analysis

Louis Arighi Ben Bromiel Sue Bachman

Bill Bogner Brian Chaille Saada Hamdy

Kevin Rennels Brad Chapin Troy Foster

Amy Russell Robert Gardner Sofia Lazovski

Susan Shaw Sandy Jones Matt Lowell

James Slowikowski David Preston RuthAnn Nicols

Josh Stevens Mary Richardson Todd Peters

Marguerite Tan Amy Russell Lavany Reddy

Ryan Williams Susan Shaw Lauren Sievers

Loretta Skowron

Kay Surratt

Dan Webb

Overview

• Watershed background

– Historical nitrate-N levels in Lake Decatur

– Change in land cover

• Summary of 15-year monitoring data

• Spatial and temporal observations

• Nitrate-N trends


Lake Decatur Nitrate Levels (1967-2008)

ISWS Monitoring

Period

Lake Decatur Nitrate Levels (1967-2008)

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

Water Year

0

2

4

6

8

10

12

14

16

18N

itra

te-N

Co

ncentr

atio

n (

mg/L

)Annual Maximum Concentration

Annual Mean Concentration

Annual Minimum Concentration

MCL

Watershed Land Use/Cover

0

100

200

300

400

500

600

Acre

s (

x 1

00

0)

1940 1960 1980 2000Year

All Acres

Corn and Beans

Corn

Soybeans

Small Grains

Illinois Agriculture Statistics for Lake Decatur watershed (1925-2008)

Watershed Area = 592,000 acres

Monitoring

Period

Watershed Land Use/Cover

0

100

200

300

400

500

600

Acre

s (

x 1

00

0)

1940 1960 1980 2000Year

All Acres

Corn and Beans

Corn

Soybeans

Small Grains

Illinois Agriculture Statistics for Lake Decatur watershed (1925-2008)

Watershed Area = 592,000 acres

Monitoring

Period

Change in percent watershed area by NASS land cover categories

between 1999 & 2008

Location and

monitoring period

of stations

!.

!.

!.

!.

!.

!.

!.

!.

!<

!<

!<

!<

!<

!<

!<

!<

!<

!<

CHAMPAIGN

FORD

MCLEAN

DEWITT

PIATT

MACON

MOULTRIECHRISTIAN

BIG/LONG CREEK

Sangamon Rive

r

GOOSE CREEK

CAMP CREEK

FRIENDS CREEK

BIG DITCH

FISHER

Sangamon River

102

103

112

101

111104

106

105

Lake

Deca

tur

ClintonUrbana

±

0 3 6 9 121.5Miles

Decatur

Monticello

Rantoul

Gibson City

Sub-watershed Boundary

Major Stream

!. Stream Monitoring Station

!< Precipitation Station

101: WY 1993-2008

102: WY 1993-2008

103: WY 1993-2000

104: WY 1993-2002

105: WY 1993-2003

106: WY 1993-2003

111: WY 1993-2008

112: WY 1993-2000

Nitrate-N Concentrations

1993 1995 1997 1999 2001 2003 2005 2007Water Year

0

5

10

15

20

0

5

10

15

20

Nit

rate

Co

nc

en

trati

on

(m

g/L

)

b) Mean Concentration

0

5

10

15

20

Long Creek

Friends Creek

Sangamon River at Monticello

Lake Decatur

a) Minimum Concentration

c) Maximum Concentration

MCL

MCL

MCL

Nitrate Loads (lb/acre)

0

5

10

15

20

25

30

35

40

45

50

55

An

nu

al N

itra

te-N

Lo

ad

( lb

/acre

)

2001 2002 2003 2004 2005 2006 2007 2008

1993 1994 1995 1996 1997 1998 1999 2000

0

5

10

15

20

25

30

35

40

45

50

55

An

nu

al N

itra

te-N

Lo

ad

(lb

/acre

)

Long Creek

Friends Creek

Camp Creek

Figure ??. Annual nitrate-N load for tributary stations during Water Year 1993 - 2008.

WYannualNO3Tribs.grf

+ Data only during May 1993 - Sept 1993

+

+

0

5

10

15

20

25

30

35

40

45

50

55

An

nu

al N

itra

te-N

Lo

ad

( lb

/acre

)

2001 2002 2003 2004 2005 2006 2007 2008

1993 1994 1995 1996 1997 1998 1999 2000

0

5

10

15

20

25

30

35

40

45

50

55

An

nu

al N

itra

te-N

Lo

ad

(lb

/acre

)

Long Creek

Friends Creek

Camp Creek

Figure ??. Annual nitrate-N load for tributary stations during Water Year 1993 - 2008.

WYannualNO3Tribs.grf

+ Data only during May 1993 - Sept 1993

+

+

Monticello

Flow-weighted Nitrate-N Concentrations

1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008

Water Year

0

10

20

30

40

50

An

nu

al R

un

off

(in

ch

es)

an

d N

itra

te-N

Yie

ld (

lb/a

cre

/ye

ar)

4

8

12

16

20F

low

We

igh

ted

Ave

rag

e

Nitra

te-N

Co

nce

ntra

tion (m

g/L

)Runoff: Long Creek

Runoff: Friends Creek

Runoff: Sangamon River

Load per acre: Long Creek

Load per acre: Friends Creek

Load per acre: Sangamon River

Flow-weighted Concentration: Long Creek

Flow-weighted Concentration: Friends Creek

Flow-weighted Concentration: Sangamon River

Project & long-term data period investigation

Illi

noi

s R

iver


Sangamon RiverWatershed

Sangamon River

OakfordMonticello

FriendsCreek

Long

Creek

Salt Creek

0 10 205 Miles

Project

Stations:

WY1994-2008

1994 2008

Sangamon River

At Oakford:

WY1975-2006

1975 2006

Sangamon River

At Oakford:

WY1994-2006

1994

1975

Annual Average nitrate-N concentrations

1970 1974 1978 1982 1986 1990 1994 1998 2002 2006 2010Water Year

0

2

4

6

8

10

12

Nitra

te-N

Co

nce

ntr

ation

(m

g/L

)

Long Creek WY1994-2008

Friends Creek WY1994-2008

Sangamon River at Monticello WY1994-2008

Sangamon River at Oakford WY1975-2006

Figure 30. Annual average nitrate-N concentrations at project and regional stations

Average Monthly Nitrate Runoff and Yield

OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP

Month

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Run

off

(in

ch

es)






OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP

Month

0

1

2

3

4

5

6

Nitra

te-N

Yie

ld (

lbs/a

cre

)






MMGraphFig36.grf

Figure 36. Long-term mean monthly nitrate-N load per acre for the

project and regional stations

Runoff

Load

1830 1850 1870 1890 1910 1930 1950 1970 1990 2010

Year

25

30

35

40

45

50

55

60

65

Pre

cip

ita

tio

n (

inch

es)

Annual Total Precipitation

5-year Moving Average


a) ILLINOIS

Mo

nito

rin

g P

eri

od

Annual and Moving Average Precipitation

1830 1850 1870 1890 1910 1930 1950 1970 1990 2010

Year

20

25

30

35

40

45

50

55

60

65

Pre

cip

ita

tio

n (

inche

s)

Annual Total Precipitation



Figure TITLE

MMGraphPrecipFigs.grf

b) DECATUR

Mo

nito

rin

g P

eri

od

Annual and Moving Average Precipitation

Discharge, Concentration, & Yield Trends

Significant Trends Based on Kendall-Tau Test (Orange), T-Test (Blue),

and Hotelling-Pabst Test (Grey), for Variable Confidence Levels

Observations

• Monitoring period was wet:

– 8 of 15 years above 30-yr mean annual precipitation

– Monticello 100-yr streamflow record shows 4 of top 11 total annual discharges occurred during monitoring

• Nitrate-N

– Concentrations decreased as drainage area increased

– Loads were disperse around watershed and varied from year to year

• Project stations had no significant trends in discharge and yields

• Based on trends during project and long-term data analysis, possible no significant change in nitrate yields for Lake Decatur watershed since 1975

http://www.isws.illinois.edu/pubdoc/

CR/ISWSCR2010-07.pdf

Thank you!

http://www.isws.illinois.edu/pubdoc/CR/ISWSCR2010-07.pdf




Documents

Lake Decatur Watershed 15-year Monitoring: Nitrates and Trendsilrdss.isws.illinois.edu/pubs/govconf2011/session3c/Keefer.pdf · Lake Decatur Watershed 15-year Monitoring: Nitrates