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Hanalei Bay Watershed


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by Mr. Matt Rosener
Hydrologist, Hanalei Watershed Hui
at the Hawaii Water Quality Conference 2008

Published in: Economy & Finance, Travel
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Hanalei Bay Watershed

  1. 1. Water Quality in the Hanalei Bay Watersheds Matt Rosener Hydrologist Hanalei Watershed Hui
  2. 2. Location
  3. 4. Place of extraordinary natural beauty…
  4. 5. … steeped in cultural traditions
  5. 6. Hanalei Watershed Hui <ul><li>Small, non-profit conservation organization </li></ul><ul><li>Working to protect the resources of Hanalei </li></ul><ul><li>Do this by: </li></ul><ul><ul><li>Studying watersheds, identifying problems </li></ul></ul><ul><ul><li>Planning for solutions & implementing them </li></ul></ul><ul><ul><li>Education & outreach programs </li></ul></ul>
  6. 7. Hanalei Bay Watersheds TMDL Study <ul><li>Draft TMDL completed Jan. ’07 </li></ul><ul><li>Tetra Tech was contractor </li></ul><ul><li>Hanalei Watershed Hui did storm sampling </li></ul><ul><li>DOH presented to community Feb. ’07 </li></ul>
  7. 8. Following tables/graphics from the TMDL report
  8. 9. TMDLs and Load Targets for the Hanalei Bay Watersheds <ul><li>Draft TMDLs developed for enterococcus and turbidity (linked to TSS) </li></ul><ul><li>Draft Load Targets developed for nutrients (TP, TN, NH 4 , NO x ) </li></ul>
  9. 14. ~ 90% of land area is forest or scrub/shrub land cover ~ 90% of TSS and Enterococcous loads attributed to these areas
  10. 15. Are the Load Reduction Prescriptions Realistic? <ul><li>Possibly for Enterococcous, esp. if human source is dominant and effectively addressed </li></ul><ul><li>Probably not for suspended sediment </li></ul><ul><li>Why not? </li></ul>
  11. 17. Nature of place to experience frequent high rainfall/runoff and infrequent extreme flooding event Entire Hanalei coastal plain is part of Hanalei R./Waioli Str. floodplain
  12. 18. Beach Monitoring –Entero Stats 2003
  13. 20. Stream Monitoring –Entero Stats 2003
  14. 21. What are we doing about it? Hanalei Watershed BMPs
  15. 23. <ul><li>County cesspool & septic system </li></ul><ul><li>up-grades at beach parks </li></ul>
  16. 24. New Septic Systems Installed at County Facilities in Hanalei <ul><li>At Hanalei Baseyard on 2 March 2006 </li></ul><ul><li>At Pavilion (men’s) on 8 March 2006 </li></ul><ul><li>At Pavilion (women’s) on 9 March 2006 </li></ul>
  17. 25. HWH replacing septic upgrades for homes in/near riparian areas
  18. 28. All waters turbidity-impaired
  19. 30. Trail Restoration
  20. 31. Next Steps <ul><li>Focused monitoring & source assessment </li></ul><ul><li>Develop Watershed-based Action Plan </li></ul><ul><li>Implement BMPs & monitor effectiveness </li></ul><ul><li>Continue water quality research programs </li></ul>
  21. 32. Mahalo
  22. 33. TMDLs and Load Targets for the Hanalei Bay Watersheds <ul><li>Draft TMDLs developed for enterococcus and turbidity (linked to TSS) </li></ul><ul><li>Draft Load Targets developed for nutrients (TP, TN, NH 4 , NO x ) </li></ul>
  23. 34. Technical Approach <ul><li>Developed a modeling framework to assess cause-effect relationship between source contributions and response of the river, estuary, and bay </li></ul><ul><li>Tested/calibrated the model using available flow and water quality monitoring data at multiple locations </li></ul><ul><li>Used model to determine source loads that enable river, estuary, and bay to achieve applicable water quality criteria at all times </li></ul>
  24. 35. Modeling Framework <ul><li>Watershed model: EPA’s Loading Simulation Program in C++ (LSPC) </li></ul><ul><ul><li>Watershed hydrology and flow in Hanalei River </li></ul></ul><ul><ul><li>Erosion from the land surface and mass transport in the river </li></ul></ul><ul><ul><li>Bacteria and nutrient loading from the land surface and transport in the river </li></ul></ul><ul><li>Estuary and bay model: EPA’s Environmental Fluid Dynamics Code (EFDC) </li></ul><ul><ul><li>Freshwater inputs from watershed model used as boundary condition </li></ul></ul><ul><ul><li>Fate and transport of bacteria, nutrients, and TSS in the Hanalei Estuary (tidal) and Hanalei Bay </li></ul></ul><ul><ul><li>1-dimensional representation of the estuary </li></ul></ul><ul><ul><li>2-dimensional representation of the bay </li></ul></ul>