1. Water Quality Control Commission Hearing June 8, 2015
IN THE MATTER OF THE ADOPTION OF REVISED WATER QUALITY CLASSIFICATIONS, STANDARDS AND DESIGNATIONS FOR MULTIPLE SEGMENTS IN THE CLASSIFICATION AND NUMERIC STANDARDS FOR SOUTH PLATTE RIVER BASIN, LARAMIE RIVER BASIN, REPUBLICAN RIVER BASIN, SMOKY HILL RIVER BASIN, REGULATION 38 (5ccr ) Site Specific Mercury Standard for Segment 16i of the Upper South Platte Subbasin
Water Quality Control Commission Hearing June 8, 2015

2. April 2013 WQCC Rulemaking Hearing
Proposal
In 2013, Suncor proposed a site-specific mercury (Hg) standard, based on fish tissue analysis and bioaccumulation factors to be applied below Suncor’s discharge
Results
Concern from the Agencies (EPA, CPW, WQCD) on data and calculations
WQCC directed Suncor to collect more data
Adopted “current condition” temporary modification for Hg for Segment 16i, set to expire in 2017, to provide time to resolve uncertainty about the appropriate underlying standard

3. In 2013 and 2014, Suncor: 2013 – 2104 Sampling
Developed a Sampling and Analysis Plan approved by EPA, WQCD and CPW (“Agency’s”)
Conducted fish tissue sampling for the largest fish caught during multiple sampling events over variable flow conditions and seasons
Conducted monthly water column sampling for total mercury (TotHg) and methylmercury (MeHg)
Collected tissue samples as skinless filets and analyzed for TotHg
Submitted annual progress reports to the WQCD

4. Sand Creek Study Locations

5. Suncor’s Proposal - 2015 Rulemaking Hearing
Suncor developed an alternate site-specific standard of µg/L for total mercury based on comments in the WQCD’s RPHS, using the following data and calculations:
Geomean water column TotHg concentration for Site SW2-1 (downstream of discharge)
Weighted geomean fish TotHg concentration using green sunfish and common carp for Site SW2-1
Site-specific BAF using the weighted geomean fish tissue concentration and the geomean water column concentration
Calculate a TotHg standard using site-specific weighted BAF and the 0.3 mg/kg fish tissue criterion

6. 2015 Rulemaking Hearing - Agency Proposal
WQCD developed an alternate site-specific standard of µg/L, based on USGS methodology, using the following data and calculations:
Mean fish tissue concentration for each species
Weighted 85th percentile MeHg water concentrations from SW2-1 and SWP (upstream of discharge)
Site-specific BAF for each species
Utilize species with the highest BAF for MeHg (green sunfish) and calculate a MeHg standard, then translate to a TotHg water column standard
Because the 85th percentile is used in the calculations, 303(d) assessment would be based on the weighted 85th percentile of TotHg data

7. Agreement between Suncor and the WQCD
Summary
Agreement between Suncor and the WQCD
Suncor agrees to the site-specific standard of µg/L TotHg
The standard is protective of the 0.3 mg/kg fish tissue criterion for the highest potential for bioaccumulation
Assessment should occur using the weighted 85th percentile of TotHg data from Sites SW2-1 and SWP

8. Questions

9. EXTRA SLIDES

10. Water Column Concentrations
Total Mercury Concentrations in Sand Creek

11. Fish Tissue Concentrations
Methyl Mercury Fish Tissue Concentrations in Sand Creek

12. Mercury Concentrations - Effluent
Effluent Total Mercury Concentrations

13. Predicted South Platte River Concentrations
Predicted South Platte River Total Mercury Concentrations

14. Fish Length and Abundance