1. MEAD LAKE TMDL CRITIQUE Alicia Allen and Nick Grewe

2. Mead Lake  Shallow eutrophic lake  Mean depth 1.5 m, maximum depth 5 m  Drains 248 km 2 of west central Wisconsin  South Fork Eau Claire River is the primary source of surface water inflow  Mead Lake was placed on 303(d) list in 1998 due to sediment and Phosphorous  In 2008 was updated as a result of habitat degradation, pH exceedance, and excess algal growth in the summer

3. Issues  Sediment enters from South Fork Eau Claire River  Phosphorous bound to sediment particles transfers Phosphorous to lake bed  Severe algal blooms during growing season (May- October)  Removal of CO 2 through photosynthesis raises pH

4. Goal  Reduce sediment loading  Reduced sediment will decrease Phosphorous load  Reduced Phosphorous will decrease algal blooms  Algal bloom control will address pH exceedance and degraded habitat  Improve for recreational purposes

5. Water Quality Standards  Wisconsin has no numeric criteria for Phosphorous and sediment  Narrative criteria: The following should not be present in such amounts as to interfere with public rights in waters of the state  Substances that will cause objectionable deposits on the shore or in the bed of a body of water  Floating or submerged debris, oil, scum, or other materials  Materials producing color, odor, taste, or unsightliness  93 ppb P- site-specific target developed using criterion

6. Water Quality Standards  pH standard: “The pH shall be within a range of 6.0-9.0, with no change greater than 0.5 units outside the estimated natural seasonal maximum and minimum”  Based off the designation of Mead Lake as fish and other aquatic life uses  TMDL was not based off of this standard, but was checked against it at the end

7. Background of Study  2 year study (2002-2003) of water quality in Mead Lake and South Fork Eau Claire River  Focused on external loading of suspended sediments and nutrients from river, internal P fluxes from lake sediment, and in-lake water quality  South Fork Eau Claire River  Continuous flow monitoring  Bi-weekly and storm event water quality sampling  TSS, total N, total P, soluble reactive P

8. Background of Study  Mead Lake  Bi-weekly testing at 3 locations from May-September  Total N, Total P, soluble reactive P, chlorophyll  In-situ testing for temperature, DO, pH, and conductivity

9. Study Findings Trophic State Index Year Secchi (m) Chla (ug/l) TP (ug/l)TSI SD TSI CHLA TSI TP 20020.5250.813069.264.565.8 20030.776.21256567.665.5  TSI>50 = Eutrophic  River accounted for 54% of Total P load to Mead Lake  Exceedance of WQ criteria for pH generally correspond to chlorophyll levels > 70 ug/L Sediment Load (tons) YearSeasonalAnnual 2002428774 2003189609

10. Land Use Modeling  Modeled using SWAT  Simulated runoff, sediment, and P loading  Utilized to assess the effectiveness of reducing phosphorous and sediment loads to Mead Lake  Used  Detailed land management information  2002 farm survey of 74 farms  1999 land use survey  3 crop rotations were used  Calibrated for flows and load data using 2002 values

11. Land Use Land CoverArea (hectares)Area % Cropped Farmland10,38341.38 Forest7,96431.47 Grassland/Pasture2,69010.72 Wetland2,4239.66 Urban/ Impervious1,2144.84 Farmsteads2420.97 Water1720.69

12. Conclusions Scenario Seasonal Total P Load (lbs) P Load Reduction (%) Baseline 5,500 Reducing soil P (25 ppm) 4,73014% Reducing Soil Erosion (50% reduction in USLE) 4,73014% Reduce manure P by 38% (animal dietary changes) 5,2804% Combination: reducing soil P, soil erosion control and manure management 4,01527% Winter Rye Little change5% Continuous pasture (rotational grazing) 4,34521%  Change in P export due to different management and land use changes

13. Lake Modeling  Modeled using BATHTUB  Used various P loading scenarios to predict changes in  Total P  Chlorophyll  Secchi transparency  Algal bloom frequency  Calibrated using 2002 data and compared to collected 2003 data

14. Conclusions 30 % reduction in external P load decreases Total P by 24%

15. Loading Capacity  TMDL Load Capacity = WLA + LA + MOS  WLA = Wasteload Allocation  LA = Load Allocation  MOS = Margin of Safety  WLA = 0 because no point sources  Load Capacity = LA + MOS

16. Load Allocation  Phosphorous  30% reduction in seasonal P load = 3850 lb  35% reduction in annual P load = 8600 lb  Sediment  30% seasonal decrease = 233 tons  30% annual decrease = 826 tons  Only focused on external P load. Internal load will be addressed after external load is controlled and funds become available

17. Margin of Safety  Load reduction goals greater than what is needed  Seasonal- 200 lb MOS  Annual- 480 lb MOS  MOS from non-point source control programs not incorporated into SWAT model  Implementation of Conservation Reserve Program (CRP)  Barnyard BMP implementation- barnyard runoff not incorporated into the model

18. Implementation  Utilize preexisting programs  Federal, state, and county  Use existing employees  Funding from public and private investors  Public includes: WDNR, Mead Lake District, Clark County Land Conservation Department  Additional BMP funding available  Volunteer water quality monitors

19. Suggested Further Treatment Methods  Three methods for reducing internal P loading  Alum Treatment: Treat lake bottom before going anoxic and releasing P Floc generation leads to P binding and becoming unavailable for plant uptake (aluminum phosphate) Only administered after external loading controlled External P would cover alum bed

20. Suggested Further Treatment Methods  Aeration  Prevent stratification and anoxic layer  Lines placed in deep holes to bubble air  Operation costs may be high due to electricity demands  Siphoning  Siphoning water from bottom before going anoxic  Where does it go?  Dry years may not have enough flow

21. Continued Monitoring  Data collection to begin 5 years after implementation  Water quality monitored for 2 years at South Fork Eau Claire River  Lake water quality data collected  Assume same time period?  Update land use data  Run updated SWAT and BATHTUB  Expensive

22. Critique of TMDL  No set 303(d) standards for WI  Advantage Each lake will have unique characteristics No standard allows for tailored goal based on feasibility  Disadvantage Difficult comparison between lakes No “blue print” for TMDL More analysis required to develop specific goal

23. Critique of TMDL  Not including barnyard runoff in SWAT  Runoff from livestock is a major source of phosphorus  Land use data from 74 farmers  Load allocation may be underestimated  No reason as to why it was omitted from SWAT  Assuming BMPs will be enough to address MOS  MOS may be off due to barnyard runoff exclusion  Only 10 months of bi-weekly water quality data for calibration  Is this data really representative of average loads?

24. Summary Load Capacity (% Reduction) Sediment (tons)Phosphorous (lb) Seasonal233 (30)3850 (30) Annual826 (30)8600 (35)  Will also decrease pH and algal blooms significantly  Seasonal loads have the most impact, but including annual load capacity will address all time periods  Inclusion of barnyard runoff into SWAT would have better represented load reduction results.  As of 2008, TMDL approved.