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Moore’s Creek and Lodge Creek, Meadow Creek and Schenks Branch Benthic Impairments

Moore’s Creek and Lodge Creek, Meadow Creek and Schenks Branch Benthic Impairments. Technical Advisory Committee Meeting (revised) Gene Yagow December 9, 2010. Overview. Basis for Impairment Nature of the Impairment Stressor Analysis Eliminated Stressors Possible Stressors

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Moore’s Creek and Lodge Creek, Meadow Creek and Schenks Branch Benthic Impairments

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  1. Moore’s Creek and Lodge Creek, Meadow Creek and Schenks Branch Benthic Impairments Technical Advisory Committee Meeting (revised) Gene Yagow December 9, 2010

  2. Overview • Basis for Impairment • Nature of the Impairment • Stressor Analysis • Eliminated Stressors • Possible Stressors • Most Probable Stressors • Next Steps

  3. Basis for Impairment

  4. Basis for Impairment Moore’s Creek (MSC) Lodge Creek (XRC) Meadow Creek (MWC) Schenks Branch (SNK) Unnamed Trib (XSN) SCI = Stream Condition Index

  5. Nature of the Impairment • Extent of the impairment • Benthic organism (fish food) inventory • Diversity • Pollution tolerance • Abundance • Habitat metrics

  6. Extent of the Benthic Impairment

  7. Benthic Organism InventoryMoore’s Creek and Lodge Creek

  8. Benthic Organism InventoryMeadow Creek and Schenks Branch

  9. Habitat MetricsMoore’s Creek and Lodge Creek Lodge Creek Moore’s Creek

  10. Habitat MetricsMeadow Creek and Schenks Branch Schenks Branch Meadow Creek Unnamed Tributary, Schenks Branch

  11. Stressor Analysis • Benthic impairment does not specify pollutant(s) • Review existing data • Weight-of-evidence approach • Identify potential sources

  12. Insufficient stream buffers Barren areas Impervious Areas Industrial/ Commercial Transportation Sources: Residential Agriculture VPDES dischargers Unstable stream banks Sewer system overflows Stream bank trampling by livestock Construction Nutrient Enrichment Stressors: PAHs Organic Enrichment Erosion Increased TSS Increased high flows Increased sedimentation Removal of organisms by flushing or scouring Embeddedness; loss of in-stream habitat Loss of bank habitat Altered food source Aquatic mortality Causes: Shift in benthic macroinvertebrate community Effects: Interaction of Multiple Stressors

  13. Eliminated Stressors • Ammonia • Metals • pH • Temperature

  14. Eliminated Stressors • Ammonia

  15. Eliminated Stressors (cont.) • Metals

  16. Eliminated Stressors (cont.) • pH

  17. Eliminated Stressors (cont.) • Temperature

  18. Landuse Distribution

  19. Possible Stressors • Hydrologic Modifications (Moore’s Creek) • Nutrients • Organic Matter • PAHs • TDS/conductivity • Toxics

  20. Hydrologic Modifications (Moore’s Creek only) • Evidence of stress: • Several minor impoundments are in the headwater tributaries • Impervious area (8.1%) concentrated near outlet • Evidence of minimal impact: • No irrigation (golf courses?) or other major water withdrawals • No major channelization

  21. Nutrients • Evidence of stress: • Dominant organisms – hydropsychidae and chironomidae – typical of enriched streams (All) • Poor to marginal riparian vegetationhabitat metric values • Average percentage of the 2 Dominant Species > 75% (All) • Occasional TP exceeding “threatened” levels (Moore’s) • High nutrient concentrations from Moore’s Creek STP • Frequent sewer system overflows (Lodge) • Evidence of minimal impact: • All DO concentrations above minimum WQ standard (All) • No excessive diurnal DO fluctuations (Meadow, Schenks) • Absence of TP exceedences (Meadow, Schenks)

  22. Organic Matter • Evidence of stress: • Most MFBI values > 5.0, indicating organic enrichment (All) • Dominant organisms – hydropsychidae and chironomidae – typical of enriched streams (All) • Low SC/FC ratios and high %filterer-collectors (SNK) • Evidence of minimal impact: • All DO concentrations above minimum WQ standard (All) • No excessive diurnal DO fluctuations (MWC, SNK) • High SC/FC ratios and low %filterer-collectors (MSC, MWC)

  23. PAH Introduction • Polycyclic Aromatic Hydrocarbons • Chemical compounds with 4- to 7-ring hydrocarbon structures, usually present as complex mixtures • Some are highly potent carcinogens • Ubiquitous contaminants derived primarily from combustion of organic matter and fossil fuels • While individual PAHs can cause toxicity, multiple congeners at lower levels may also have cumulative effects

  24. PAHs

  25. PAHs (cont.)

  26. PAHs (cont.)

  27. PAHs (cont.)

  28. PAHs (cont.) Select Statewide DEQ Probability Monitoring Data Many non-impaired streams have detectable levels of PAHs.

  29. PAH Potential Sources Pollutant Response Program (PReP) Incidences

  30. PAH Potential Sources (cont.) Reported Petroleum Releases

  31. PAH Potential Sources (cont.) VPDES Permitted Discharges

  32. PAH Potential Sources (cont.) • Sanborn maps indicate multiple historic and current oil processing and refining facilities in Schenks Branch watershed • Recent literature points to coal-tar based asphalt sealers as a major source of urban PAHs

  33. PAH Summary • Schenks Branch appears to be the primary origin of PAHs, though the exact sources are unknown • Many potential sources are available • PAHs do adsorb to sediment, with low partitioning to the water column • Baseflow is typically minimal in Schenks, as is the sediment it could transport • Storm runoff that transports sediment probably increases transport of PAHs • Habitat and hydrologic modifications are probably more primary stressors

  34. TDS/Conductivity TDS Conductivity Screening Value

  35. Toxics • Evidence of stress: • Low %shredders (All) • Known VPDES dischargers • Abundance of historical industrial uses in the area • Many reports of petroleum releases (All) • Some Mean-PEC quotients > 0.5 (MWC, SNK) • Evidence of minimal impact: • Abundance of organisms (All) • No exceedences of metals or pesticide sediment PECs or water column Aquatic Life or Human Health criteria (All)

  36. Most Probable Stressors

  37. Hydrologic Modification Evidence • High % imperviousness • Lodge Creek: 30.7% • Meadow Creek: 31.9% • Schenks Branch: 36.2% • Channelized headwater stream segments (Schenks Branch) • Sewer system overflows (Lodge Creek)

  38. Sediment Evidence Already part of the Rivanna River Sediment TMDL.

  39. Insufficient stream buffers Barren areas Impervious Areas Industrial/ Commercial Transportation Sources: Residential Agriculture VPDES dischargers Unstable stream banks Sewer system overflows Stream bank trampling by livestock Construction Nutrient Enrichment Stressors: PAHs Organic Enrichment Erosion Increased TSS Increased high flows Increased sedimentation Removal of organisms by flushing or scouring Embeddedness; loss of in-stream habitat Loss of bank habitat Altered food source Aquatic mortality Causes: Shift in benthic macroinvertebrate community Low % haptobenthos Hydropsychidae dominant in Fall Low % sensitive species Chironimidae dominant in Spring High % filterer-collectors in Spring Effects: Conceptual Model: Moore’s Creek and Lodge Creek

  40. Multiple Benefits from BMPs

  41. Relationship to other Watershed Planning Efforts • Other planning efforts addressing sediment: • Rivanna River Sediment TMDL • County and City Stream Assessment Projects • Chesapeake Bay Sediment TMDL • Others? • Complimentary Implementation Efforts • TNC stream restoration on Meadow Creek • RWSA sewer interceptor Project (Meadow Creek) • Moore’s Creek Bacteria TMDL Implementation Plan • Others?

  42. Next Steps • Receive and review comments on selected stressors • Prepare sediment load estimates for existing conditions and target TMDL loads • Initiate stakeholder meetings to assess BMPs needed to reduce loads from various source sectors

  43. Contact Information • Gene YagowBiological Systems Engineering Dept. 306 Seitz Hall (0303)Virginia TechBlacksburg, VA 24061eyagow@vt.edu540-231-2538

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