Phosphorus and Lake Erie: Where does it come from??
Laura Johnson Algal blooms were prevalent in the 1960s and 1970s and the lake appeared to recover in the early 1990s
1971
Scavia et al. 2014, JGLR Algal blooms returned to Lake Erie in the early 2000s…
2011
Scavia et al. 2014, JGLR Algal blooms returned to Lake Erie in the early 2000s… with 8 of the largest blooms over the past 11 years
2011
Toledo drinking water crisis River monitoring has been a huge asset Heidelberg Tributary Loading Program Sampling began in 1974 in the Maumee and Sandusky
Each station paired with a USGS gage
Goal is to quantify watershed loads Samples collected 3x a day! Colorimetry for TP, DRP, TKN,
NH4, Si
Ion chromatography for
NO3, NO2, Cl, Fl, SO4
Suspended Sediments How did Lake Erie improve originally? Load is the product of concentration and flow
Load Mass/time Metric tons/year
Concentration
Mass/H2O volume mg/L
Flow or Discharge
H2O volume/time ft3/s (CFS) How to estimate nonpoint sources and total loads
Measured watershed output (or load) = NPSup + PSup NPSup = Measured watershed output (or load) – PSup
Total watershed output (or load) = Measured watershed output + (NPSdn + PSdn)
Assumes NPSup = NPSdn
Indirect PS
Direct PS
Maumee
Maumee is the largest tributary to any of the Great Lakes Most P and N comes from land runoff Maumee River Total Phosphorus Total Nitrogen Permitted Septic Septic Permitted discharges discharges
Nonpoint Nonpoint
OEPA report 2018 Maumee River watershed is 72% row crop agriculture Particulate Dissolved Total
Total P = particulate P + dissolved P Maumee River trends
• Particulate P has decreased over time • Dissolved P has increased almost 2 fold since the mid- 1990s • Nitrate-nitrogen has decreased since 2000
Raisin (50%) Sandusky (78%)
Cuyahoga (9%)
Maumee (72%) Honey (81%)
Rock (72%)
5 year running average Where does dissolved phosphorus come from? Maumee River = non-point sources Cuyahoga River = point sources
*note change in scale Where does dissolved phosphorus come from? Maumee River = non-point sources Cuyahoga River = point sources
Cumulative load = sum of daily loads Tracking change in loads and flow-weighted mean concentrations
700 2000-2017 600 2018
500
400
300
200
100
Dissolved P load (metric tons) (metric load P Dissolved 0 0 1 2 3 4 5 6 Discharge (km3)
The 2018 load is where we would expect based on discharge Load = Discharge x FWMC FWMC = Load / Discharge Tracking change in loads and flow-weighted mean concentrations
700
600 2000-2017 2018 500
400
300
200 Loading 100 target FWMC
Dissolved P load (metric tons) (metric load P Dissolved 0 target 0 1 2 3 4 5 6 Discharge (km3)
The 2018 load is where we would expect based on discharge Load = Discharge x FWMC FWMC = Load / Discharge Tracking change in loads and flow-weighted mean concentrations
700 Chesapeake Bay (Testa et al. 2018) 600 2000-2017 2018 500
400
300
200
100
Dissolved P load (metric tons) (metric load P Dissolved 0 0 1 2 3 4 5 6 Discharge (km3)
The 2018 load is where we would expect based on discharge Load = Discharge x FWMC FWMC = Load / Discharge The river is tightly linked to the lake
2011
Index Bloom Severity Severity Bloom
2012
2011
Index Bloom Severity Severity Bloom
2012
2011
Index Bloom Severity Severity Bloom
2012 The size of the bloom is related to Maumee River phosphorus exports from March - July
Discharge Total P
Dissolved P Total bioavailable P
- Stumpf et al., 2016 JGLR *note, there is no relationship with TN, NO3 , or TKN Maumee River P loads vary with discharge indicating strong hydrologic control on runoff 2018 Western Lake Erie Bloom Severity Forecast
• Predicts a 6 out of 10 with a possible range of 5–7.5
• Similar to 2008-2010 or 2014
* We can forecast bloom size but not toxicity! Peak bloom extent from satellite 2002-2017 2018
2018 Western Lake Erie Bloom Severity Forecast
• Predicts a 6 out of 10 with a possible range of 5–7.5 • Actual was 3.6 • Similar to 2016
Why?? Lack of scum? Late summer storms? Early bloom formation?
Why has dissolved phosphorus increased??
• Agriculture is applying at or below phosphorus removal levels • Watershed P exports from agriculture are only ~1% of inputs A lot of fields are leaking a little bit of dissolved P 4R nutrient stewardship principles
Next steps: • Control water through drainage water management and improving soil health • For legacy fields, add a P filter at the end of a tile drain • P filters in streams have massive challenges
Lower WWTP effluent nutrient levels improves local water quality Ohio River tributaries have much higher contributions from point sources
Ohio River Tribs
OEPA report 2018 Summary
• The return of blooms in Lake Erie is associated with increased loads and concentrations of dissolved phosphorus
• The primary source of dissolved phosphorus is agriculture rather than point sources
• Technology used to reduce effluent phosphorus or particulate concentrations could be useful as a field-side best management practice
• Ohio is expected to continue to reduce phosphorus limits on effluent, even in Lake Erie, and these reductions would greatly improve local water quality Special thanks to all our support! Thanks! Laura T. Johnson Director National Center for Water Quality Research Heidelberg University 310 E. Market Street Tiffin, OH 44883 [email protected] 419.448.2056 http://www.ncwqr.org https://www.facebook.com/ncwqr http://www.LakeErieAlgae.com https://www.blueaccounting.org/issue/eriestat