This document summarizes a presentation on phosphorus loading trends in Lake Erie. It finds that while point source phosphorus loads have significantly decreased due to sewage treatment upgrades, nonpoint source loads from agricultural runoff have not declined as sharply and show more annual variability. Specifically, the Maumee and Sandusky Rivers in Ohio export high levels of dissolved reactive phosphorus due to accumulation in surface soils under no-till practices. Reducing soil test phosphorus levels could help lower phosphorus losses to runoff.

1. Lake Erie LaMP Public Forum, Erie, PA
November 6-7, 2009
Recent Trends in
Phosphorus Loading to Lake Erie:
Role of Changing Agricultural Production Practices
David Baker, Senior Research Scientist
National Center for Water Quality Research
Heidelberg University, Tiffin, OH

2. Phosphorus: A major problem for Lake Erie
1. Sources: Point and Nonpoint
2. Forms of Phosphorus: Particulate and Dissolved
Particulate + Dissolved = Total Phosphorus
3. Bioavailability of Phosphorus:
Particulate ~ 30%
Dissolved ~ 100%
4. Loading characteristics:
Point sources -- ~ constant daily rate
Nonpoint sources – pulsed during runoff events

3. The Lake Erie Watershed: Current Land Use
Excessive
phosphorus loads
a primary cause

4. Total Phosphorus Loads to Lake Erie
30,000
Lake Erie Target Load for Total
Total Phosphorus, Metric Tons
25,000 Phosphorus set at 11,000 metric tons
20,000
15,000
10,000
5,000
0
1967 1972 1977 1982 1987 1992 1997 2002 2007
Water Year, 1967 - 2007
1. Obvious downward trend from 1967 – 1988.
2. From 1987 – 2007, trends, if present, much less certain.

5. Total Phosphorus Loads to Lake Erie
30,000
Total Phosphorus, Metric Tons
25,000
20,000
15,000
10,000
5,000
0
1967 1972 1977 1982 1987 1992 1997 2002 2007
Water Year, 1967 - 2007

6. What
happened?
Let’s take a closer look at phosphorus
loading to Lake Erie --
Especially from Northwestern Ohio and
the Sandusky and Maumee Rivers

7. What are the major sources of phosphorus that enter Lake Erie?
Lake Erie Total Phosphorus Loading by Major Source
Lake Huron Atmosheric Point Source
Nonpoint Source Unspecified
30,000
Total Phosphorus, metric tons
25,000
20,000
15,000
10,000
5,000
0
1967 1972 1977 1982 1987 1992 1997 2002 2007
Water Year, 1967-2007
Data from Rockwell and Dolan

8. 14000
Point Source Nonpoint Source
12000
Total Phosphorus, metric tons
10000
Phosphorus removal at municipal
sewage treatment plants.
8000
An $8.8 billion dollar investment
6000 between 1972 and 1985.
4000
2000
0
1967 1971 1975 1979 1983 1987 1991 1995 1999 2003 2007
Rapid declines through 1982.
Much slower declines from 1982 to 2007
Note the small year to year variability in point source loads

9. 14000
Point Source Nonpoint Source
12000
Total Phosphorus, metric tons
10000
8000
6000
4000
2000
0
1967 1971 1975 1979 1983 1987 1991 1995 1999 2003 2007
Note the large annual variability in nonpoint source phosphorus loading

10. Lake Erie Phosphorus Loads
External Phosphorus Average Percent of
Sources to Lake Erie Phosphorus Total
1981 – 2007 Water Load, Phosphorus
Metric tons/yr Load
Years (27 Years)
Nonpoint sources 6,467 63.1% 3
Point sources 2,201 21.5% 1
Atmospheric
Deposition 496 4.8%
Upper Lakes 1,080 10.5%
Total Average Annual
Load 10,244 100%

11. Maumee River, Total Phosphorus Export Rate
TP export rate mtons/day
140
All Lake Erie Point Sources = 6.03 metric tons per day
Total Phosphorus, metric tons/day
120
100
80
60
40
20
0
10/01 10/31 11/30 12/30 01/29 02/28 03/30 04/29 05/29 06/28 07/28 08/27 09/26
Date, 2007 Water Year
For the total point sources entering Lake Erie from 1981 – 2007,
the average daily load has been 6.03 metric tons per day

12. In July and August
2003, three major
runoff events
occurred in the
August 18,
Maumee River (left). 2003
That summer had
the most severe
blue-green algal
blooms that had
been observed in
recent years.
Maumee River 7/1/2003 - 8/22/2003
Flow, CFS TP, mg/L as P
50,000 0.800
45,000 0.700
40,000
0.600
35,000
Flow (cfs)
0.500 TP (mg/l)
30,000
25,000 0.400 % Point
20,000 0.300 Source P
15,000
0.200
10,000
5,000 0.100 Maumee 4.9%
0 0.000 Sandusky 2.8%
7/1/03 7/11/03 7/21/03 7/31/03 8/10/03 8/20/03
Date

13. Drainage to interconnecting
channel
Area = 22.4%
point source P load = 55%
nonpoint P load = 9%
P load, all sources = 29%
Drainage to western basin
Area = 42.6%
point source load = 20%
Drainage to central and
nonpoint P load = 71% eastern basins.
P load, all sources = 48% Area = 35.0%
point source P load = 25%
nonpoint P load = 20%
P load, all sources = 23%

14. PLUARG Final Report,
1980
Pollution from Land Use Activities
Reference Group

15. Total Phosphorus
Total Total
Particulate Dissolved
Phosphorus Phosphorus
Agricultural Phosphorus Control Programs
in the Lake Erie Basin
No-till and reduced-till to reduce cropland erosion
Conservation Reserve Program, take highly erosive land out
of production
Conservation Reserve Enhancement Program – buffer strips

17. Sandusky River, Annual Loads
Sandusky R., Total Phosphorus
of Total Phosphorus Loads
Sandusky River: Total Phosphorus Loads
1200
Total Phosphorus, metric tons
1000
800
600
Calculated Directly
loads 400 measured
200 loads
0
1975 1980 1985 1990 1995 2000 2005
Water Year
Sandusky River Fremont, Sandusky River, Fremont,
Particulate of Particulate Phosphorus
Annual Loads Phosphorus Loads
Particulate Phosphorus Loads Dissolved Reactive Phosphorus Loads
Annual Loads of Dissolved Phosphorus
1200
300
Particulate Phosphorus, metric
1000 Dissolved phosphorus, metric 250
800 200
tons
tons
600 150
400 100
200 50
0 0
1975 1980 1985 1990 1995 2000 2005 1975 1980 1985 1990 1995 2000 2005
Water Year Water Year

18. Sandusky River Fremont, Sandusky River, Fremont,
Particulate Phosphorus Loads
Annual Loads of Particulate Phosphorus Dissolved Reactive Phos. Loads
Annual Loads of Dissolved Phosphorus
1200 300
Particulate Phosphorus, metric
Dissolved phosphorus, metric
1000 250
800 200
tons
tons
600 150
400 100
200 50
0 0
1975 1980 1985 1990 1995 2000 2005 1975 1980 1985 1990 1995 2000 2005
Water Year Water Year
Sandusky R., Bioavailable Phosphorus Loading
Sandusky R. Bioavailable Phos. Loads
Bioavallable Soluble Phos. Bioavailable Particulate Phos.
500
Bioavailabe Phos, metric tons
400
300
200
30%
100 110%
bioavailable
0
bioavailable
1975 1980 1985 1990 1995 2000 2005
Water Year

19. Maumee River, Annual Loads Maumee R., Annual Loading,
Particulate Phosphorus Loads
of Particulate Phosphorus Dissolved Dissolved Reactive Phosphorus Loads
Reactive Phosphorus
3,500 1000
Particulate Phosphorus, metric
900
Phosphorus, metric tons
3,000
800
Dissolved Reactive
2,500 700
2,000 600
tons
500
1,500 400
1,000 300
200
500
100
0 0
1975 1980 1985 1990 1995 2000 2005 1975 1980 1985 1990 1995 2000 2005
Water Year Water Year
Maumee R. Bioavailable Phosphorus Loading
Maumee River, Bioavailable Phosphorus Loads
Bioavailabe Soluble Phos. Bioavailable Particulate Phos.
2000
Bioavailable Phosphorus
1600
Loads, metric tons
1200
Dissolved
30% bioavailable
bioavailable 800
equals
400 110% of
0 DRP
1975 1980 1985 1990 1995 2000 2005
Water Year

20. Why has the dissolved phosphorus
loading from the Sandusky and Maumee
rivers dropped and then increased so
much?

21. Figure 18. Analysis of Ohio commercial phosphorus fertilizer sales from 1955-2006. Source: Commercial Fertilizer Report,
published by the Association of American Plant Control Officials

22. No-till and reduced-till can increase
dissolved phosphorus runoff.

23. Soil Testing
For Crop For Environmental
Production Runoff
Environmental
Soil Testing
Agronomic 0-2 inches
Soil Testing
Soil Testing to
0- 8 inch Evaluate
cores Stratification
Soil 2- 8 inches
Plants can generally
Dissolved phosphorus
access nutrients within
concentrations are
the top 8 inches of soil
generally proportional
to soil test P in top 2 inches

24. Critical Phosphorus Soil Test Concentrations for Corn and Soybeans
Ohio State
University
Extension
Fact
Sheet,
2007,
Watson &
Mullen

25. Agronomic Soil Testing – 381 fields in the Sandusky Watershed

26. Sandusky DRP
90% of Sandusky Soil tests are in this range.
As soil test phosphorus increases, dissolved phosphorus in runoff increases.
The higher the soil test value, the more phosphorus farmers lose to runoff.

27. Phosphorus Stratification, Comparison between top 2 inches of soil
with 0-8 inch values, 381 fields in the Sandusky Watershed
200
180
Mehlich3-P, 0-2 inches, ppm
160
140
120
100
80
60
40
20
0
0 20 40 60 80 100 120 140 160 180 200
Mehlich3-P, 0-8 inches, ppm
Phosphorus accumulates in the upper layer of soil under no-till and
reduced-till cropping practices.

28. Sandusky Watershed, Comparison of Agronomic and
Environmental Soil Tests
0-2 0-8 inch
100
90 Agronomic
Percentile of 381 fields
80 Soil Test
47 72
70
Environmental Soil Test
60
50 34 52
40
30
22 32
20
10
0
0 25 50 75 100 125 150 175 200
Mehlich 3 Phosphorus Soil Test Resuts, ppm

29. Crops in the Sandusky Watershed: 2006
Cropland Corn Beans Wheat Hay
Acres 758,630 248,430 406,210 97,980 3,670
Percent 32.7% 53.5% 12.9% 0.5%
Very low erosion rates --- 1.9 tons per acre per year for cropland
Most of the soils are classified prime farmland if drained (884,000 acres)
and prime farmland ( 158,000)
Not prime farmland – 117,000 acres

30. Average 453 kg/ha
USGS Midwestern
agricultural watershed
Maumee (582 kg/ha) data base for
Sparrow Model
Sandusky (689 kg/ha) calibration
Sandusky – higher than average suspended sediment export, even
though low erosion rates.
Cause: relatively high clay content of most cropland soils

31. Average = 0.851 kg/ha
Maumee (1.43 kg/ha)
Sandusky (1.68 kg/ha)
High total phosphorus loads in spite of 20 years of control programs to
reduce phosphorus runoff.

32. Average = 25.48 kg/ha
Maumee (25.5 kg/ha)
Sandusky ( 27.21 kg/ha)
High nitrogen export in spite of low proportion of corn in cropland.

33. Value of nutrients lost in 2007 from
Sandusky Watershed
(as measured at Tindal Bridge and using 2008 fertilizer prices)
Nitrate- nitrogen - $8,196,000
Organic nitrogen - $3,744,000
Particulate Phosphorus - $1,795,000
Dissolved Phosphorus - $602,500
Total - $14,337,500 ($17.88 per acre in watershed)

34. What strategy should be used for programs to reduce dissolved
phosphorus loading to Lake Erie from agricultural sources?
High hanging fruit High cost per unit reduction
Medium hanging fruit Medium cost per unit reduction
Low hanging fruit Low cost per unit reduction

35. Should we focus on small
Large watersheds, picking low,
Watershed medium and high hanging
fruit?
Small Watershed
319 Project focus is
often on small
watersheds ….
…supports
assessment?
Should we focus on
low hanging fruit
over large areas?
Objective: Reduce phosphorus export
Stream system from large watersheds to
Lake Erie.

36. What are the low hanging fruits relative to
reducing dissolved phosphorus runoff?
1. Drawdown or no fertilizer applications on soils with agronomic soil
test values above “maintenance range”
2. Soils with environmental soil test values above a “threshold value”
(yet to be determined).
3. Minimize fall and winter broadcast applications of fertilizers.
4. Encourage deep banding and injection of fertilizers.
5. Improve soil tilth (water infiltration and water holding capacity)
6. Continue traditional soil conservation measures.

37. Questions?

39. How do you measure nonpoint source pollution?
… the watershed approach for quantifying nonpoint pollution.
Point source input
Stream gaging/monitoring station
watershed
boundary
Assumes 100%
delivery of Total Watershed
pollutant through Export
the streams.
Total
Nonpoint source Point source
loading = watershed - inputs
output

40. The Heidelberg University Tributary Loading Program
Sampling Stations
Station Support
ODNR
Michigan DEQ
Lake Erie CREP
Great Lakes Protection
Fund
EDF/Joyce Foundation
USDA/NRCS
All stations are
associated with
USGS Stream Flow
Stations

41. These observations led to efforts to control agricultural phosphorus loading through
erosion control efforts (no-till and reduced-till) to reduce particulate phosphorus.

42. The Maumee and Sandusky
Rivers make up about 62%
of the land drainage to the 22.4 % of
Western Basin. land area
enters the
connecting
channels
River
Raisin
32.0 % of land area
drains in to the
central and eastern
basins of Lake Erie
42.6 % of land area
enters the western
basin
Maumee
River Sandusky River