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Joseph Bennett and Susan Libes

CCU’s Environmental Quality Lab: Investigation of Ocean Outfalls in Myrtle Beach and North Myrtle Beach, SC. Joseph Bennett and Susan Libes. Pipes on Beach 2 to 3 inch diameters 100 +. Outfall Pipes 60 + inch diameters 1000 + ft offshore Myrtle Beach 25 th Ave S (June 2003)

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Joseph Bennett and Susan Libes

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  1. CCU’s Environmental Quality Lab: Investigation of Ocean Outfalls in Myrtle Beach and North Myrtle Beach, SC Joseph Bennett and Susan Libes

  2. Pipes on Beach 2 to 3 inch diameters 100+ Outfall Pipes 60+ inch diameters 1000+ ft offshore Myrtle Beach 25th Ave S (June 2003) 53rd Ave. N (delayed) 14th Ave. N. (Fall 2005) North Myrtle Beach 6th Ave. S. (installed 2004) 33rd Ave S. and ? One in construction Stormwater Pipes

  3. SC DHEC OCRM Permit Requirements • Onshore Stormwater Quality Study • Characterize composition of outfall emissions • Treatment devices • In-Situ Water Quality Study • Evaluate the impact of runoff on nearshore • ?Flows • Dispersion • Discharge

  4. Potential Impacts of Concern • Bacteria • Swimming • Eutrophication • Dissolved Oxygen • ?Animals • Toxics • Salinity

  5. Potential Parameters • Enteroccoci • Dissolved Oxygen • Nutrients • Oxygen Demanding Substances (BOD5) • Chlorophyll • Turbidity • Salinity • Temperature

  6. Potential Sampling Strategies • Following rain events • Onshore • Offshore • Controls: What is normal for Long Bay? • Dry weather(onshore and offshore) • ?Geographic • Pre and post construction • Sites with little runoff • Sites with lots of runoff

  7. Stormwater Runoff Sources • Tidal Creeks (swashes) • Withers Swash: 35 to 40 cfs non-rain • Midway Swash: 10 to 15 cfs non-rain • Pipes on Beach Face • Outfall Pipes

  8. Longshore Flow

  9. What is normal?What is acceptable? • Impacts • Water Quality • Animals • Fisheries • Natural populations • Loading • Beach Pipes • Outfall Pipes • Swashes • Management • Regulatory Criteria • Benchmarks • Thresholds • Monitoring

  10. DO (ppm) % Saturation Temperature (oC) Salinity 2nd Ave N. Pier 7/20/2004

  11. Bottom Water Quality: Longitudinal Transect Along Pier

  12. 0 m 3 m ? Low DO 5 m Longitudinal Model of Hypoxic Zone Pier + 100 to 200 m

  13. Time-line • Surface Cooling: July 1 – July 30 • Rain fall • 7/9, 1.0 inches • 7/18, 2.2 inches • Sampling • 7/20: 2nd Ave N and Springmaid • 7/22: 2nd Ave N and Springmaid • 7/23: Cherry Grove and Apache + DNR transects • Flounder Jubilee • July 15 – 23 • July 23 – 28: tapered down

  14. Rain Fall Amounts Near Locations of Major Freshwater Input to Surf Zone

  15. Time-line • Surface Cooling: July 1 – July 30 • Rain fall • 7/9, 1.0 inches • 7/18, 2.2 inches • Sampling • 7/20: 2nd Ave N and Springmaid • 7/22: 2nd Ave N and Springmaid • 7/23: Cherry Grove and Apache + DNR transects • Flounder Jubilee • July 15 – 23 • July 23 – 28: tapered down

  16. pH measurements along Grand Strand, July 23, 2004

  17. Rain No Rain Rain

  18. Time-line • Surface Cooling: July 1 – July 30 • Rain fall • 7/9, 1.0 inches • 7/18, 2.2 inches • Sampling • 7/20: 2nd Ave N and Springmaid • 7/22: 2nd Ave N and Springmaid • 7/23: Cherry Grove and Apache + DNR transects • Biotic Impacts • Flounder Jubilee • Benthic invertebrate kills at Huntington Beach and Pawleys Island

  19. Causative Agents • Coastal Upwelling • Summer Cooling • Plankton Bloom • Elevated Chlorophylls • Nutrients • Stormwater Runoff • Pipes and swashes discharge on beach • Off-shore discharge pipes • Raw Sewage Spill

  20. Rain No Rain Rain

  21. P deficient growth N deficient growth Guildford and Hecky, 2000

  22. Causative Agents • Coastal Upwelling • Summer cooling • Plankton Bloom • Elevated Chlorophylls • Nutrients • Stormwater Runoff • Pipes and swashes discharge on beach • Off-shore discharge pipes • Raw Sewage Spill

  23. Causative Agents • Coastal Upwelling • Summer cooling • Plankton Bloom • Elevated Chlorophylls • Nutrients • Stormwater Runoff • Pipes and swashes discharge on beach • Off-shore discharge pipes • Raw Sewage Spill in NMB • July 13: few hundred gallons • July 21: 5000 gallons

  24. Is this a one-time event? Should we be worried?

  25. Future Frequency of Hypoxia • Frequency of Upwelling • Global Climate Change • Stormwater Runoff • Global Climate Change • Increase in population & impervious cover

  26. Potential Impacts • Hard Bottom Communities • Fisheries • Overfishing • Harmful Algal Blooms

  27. Potential Hard Bottom Habitat < 0.5 m sediment cover

  28. Hard Bottoms start 3 m Typical 4 s waves along Grand Strand constrain wind mixing to upper 3 m (Gayes, pers. comm.)

  29. Potential Impacts • Hard Bottom Communities • Fisheries • Overfishing • Harmful Algal Blooms

  30. Needs • Monitoring • Define normal for Nearshore Waters • Now using estuarine criteria • How much of these events are natural • Translate this into management guidelines • Reduction of nonpoint loads

  31. Acknowledgments • Bob Van Dolah, Mel Bell, George Reikerk, Dean Cain, SC DNR • Denise Sanger, SC DHEC OCRM • Alan Lewitus, South Carolina Algal Ecology Laboratory • Bob Pender, Ryan Day, Burroughs and Chapin Center for Marine and Wetland Studies

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