Lower Wild Rice River Turbidity: TMDL Critique

1. Lower Wild Rice River Turbidity:TMDL Critique Brent Mason, Mackenzie Consoer, Rebekah Perkins BBE 5543 November 8, 2011

2. Outline • TMDL Overview • Watershed Background • Water Quality Standards • Loading Capacity • Monitoring and Implementation • Conclusion

3. TMDL Overview Clean Water Act Section 303 (d) requirements: • Every 2 years states publish a list of “impaired” waters • TMDL report must be developed for all waters on the impaired waters list TMDL Requirements: • Provides a calculation of the maximum amount of a pollutant that a water body can receive and still meet water quality standards • Sums the loads of a single pollutant from all point and non point sources

4. Watershed Background Wild Rice River watershed: • Encompasses just over 1 million acres • Flows Across 5 Minnesota counties • Lies within three eco-regions • Impaired for Turbidity from the confluence of the South Branch of the Wild Rice River to the Red River • Impaired section of River is 30.58 miles in length and is located entirely within Norman County.

5. Wild Rice River Watershed Location

6. Wild Rice River Watershed

7. Wild Rice River Watershed Characteristics • Lower reach of Wild Rice River lies within the Lake Plain from Glacial Lake Agassiz • Extremely Flat with level deposits of lake sediment • Lower Wild Rice River is contained by low banks and has high sinuosity • Soils tend to be clays with low permeability and low internal drainage • Cropland dominates the land use of the Lower Wild Rice River • Upland is heavily drained by both ditch and tile systems

8. Wild Rice River Land Use Chart

9. Wild Rice River Watershed Land Use

10. Water Quality Standards Designated Beneficial Use: • Water body is classified as both 2B and 3B water • Chose class 2 waters: aquatic life and recreation **Higher standards Turbidity: • 25 NTU standard for natural water bodies • Surrogate measurement for Total Suspended Solids (TSS) and Suspended Sediment Concentration (SSC)

11. Turbidity Overview • Clarity of water • Caused by sediment, micro-organisms, dissolved material, and organic matter • Measurement of amount of light scattered • Measured with dimensionless unit of NTU • Blocks sunlight that fish and plants thrive on • Degrades aesthetic appeal of water body Fishschooled.blogspot.com Lenntech.com

12. Numeric Water Quality Target • Turbidity is dimensionless and cannot be used to determine sediment loads • Relationship between Turbidity and SSC needed to be derived • Using paired turbidity and SSC data, simple regression analysis was used to create a relationship between the two variables • Using this relationship: 25 NTU = 38 mg/L SSC

13. Turbidity vs. SSC Relationship • Majority of samples are at low flows and low turbidity • Limited amount of data

14. Major Assumptions • Major inconsistencies between turbidity meters • Turbidity relationship only based on one year of data and primarily at one location **Depending on how the make up of the sediment changes throughout this watershed, this relationship can vary greatly • The majority of the data was taken during low flows or winter months

15. Loading Capacity: Duration Curve Approach

16. -Only 2 sites -Underrepresented Low Flow Zone Loading Capacity: Duration Curve Approach

17. Point Sources: Wasteload Allocation TMDL = WLA + LA + MOS + RC • Four Identified Potential Sources: • 1. Municipal Wastewater Treatment Facilities (WWTFs) • 2. Construction Activities • 3. Industrial Facilities • 4. Concentrated Animal Feeding Operations (CAFOs) • Note: No MS4 permit requirements (stormwater) • All Require NPDES/SDS permit • Assumed Full Permit Compliance • Minor contributors to turbidity impairment

18. Point Sources: Wasteload Allocation • Municipal Wastewater Treatment Facilities (WWTFs) • NPDES/SDS permit = 45 mg/l TSS • Assume TSS values comparable to SSC • Similar is stream with high fine material (Gray et al, 2000) • Lower Wild Rice ~90% fine material (Macek-Rowland and Dressler, 2002) • Seasonal Discharge Windows • April-June and Sept-Dec • Assumes coincides with High Flows 1.5 tons/day for each flow zone, except low flows

19. Low Flow Allocation Exception • Loading Capacity for LOW FLOW ZONE very small • Permitted WWTF loads exceed total daily loading at low flows **Not possible because it is a component of total loads • Concentration – based on allocation to sources for low flow zone • Allocation = (flow contribution from a given source) x (45 mg/L TSS, the permit limit)

20. Point Sources: Wasteload Allocation • Construction Activities • WLA=estimated % of disturbed land= 0.17% • MPCA stormwater permit records • Industrial Facilities • 2 located in watershed • No accessible acreage data • Assumed same as Construction Activities (0.17%) • Concentrated Animal Feeding Operations (CAFOs) • 2 located in watershed • WLA=0 discharge, in accordance with permit Construction Activities + Industrial Facilities + CAFOs= .17% + .17% + 0% = 0.32% of TMDL within each Flow Zone

21. Non Point Sources: Load Allocation TMDL = WLA + LA + MOS + RC • No NPDES/SDS Permit Requirements • Major Load Contributors, occurs mostly at HIGH FLOWS • LA = Total Load Capacity-WLA-MOS • Primary Drivers in Wild Rice River Watershed • Upland Soil Erosion • Stream-Bank Erosion • Relative contributions? • Natural Processes magazine.noaa.gov

22. Margin of Safety TMDL = WLA + LA + MOS + RC • Margin of Safety (allocation uncertainty) • Four highest flow zones • Accounted for flow variability within each flow zone • Median flow-Minimum flow within each zone (standard calculation) • Low Flow Zone • Implicit MOS used (built into TMDL allocations) • Conservative assumptions • Discharge periods = High flows • Discharging below permit limits

23. Reserve Capacity TMDL = WLA + LA + MOS + RC • Reserve Capacity (future loading uncertainty) • Population Growth • 4/10 cities decline • 6/10 cities increase from 1.9% to 7.5% • WWTFs operating below loading limits, no planned expansion • RC = 0

24. Loading Allocations

25. Major Assumptions/Critiques • Flow Zone Sample Representation • NPDES/SDS permit compliance • Assume TSS values comparable to SSC • Seasonal Discharge Windows Coincide High Flow • Land Disturbance % = Loading Allocation % • Natural Background Insignificant • RC = 0

26. Wild Rice River Monitoring Plan Current Monitoring Activities • Red River Basin Watch • USGS flow monitoring and sediment analysis • MPCA milestone and condition monitoring Future Monitoring Plans • Future monitoring is being developed by the Wild Rice Watershed District with the assistance of its Flood Damage Reduction Team

27. Implementation Strategy Restoration Plan under development: • Focus of plan: Identify sources of sediment spatially • Funding for Implementation: Existing programs (Clean Water Legacy, Conservation Reserve Program, etc.) • Soil and Water Conservation District: Encourage the funding of programs that will reduce non point sources of turbidity

28. Tools to Achieve Reductions Best Management Practices (BMPs) • Filter Strips • Riparian Buffers • Grassed Waterways • Cover Crops • Conservation Tillage

29. Critique of Reduction Plan • Requires collaborative effort by many individuals and organizations • Assumes land use practices do not change significantly • Restoration costs are estimated to be in the tens of millions of dollars • Restoration tools suggested will occupy many acres of valuable farmland.

30. Conclusion • Turbidity and SSC were monitored • Numeric standard of 38 mg/L derived • Load duration curve developed to evaluate load exceedences • Monitoring and implementation plans being developed • Many assumptions were made but few assumptions had a significant impact on overall load calculations

31. Questions?