Hanalei Bay Watershed
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Transcript of Hanalei Bay Watershed
Water Quality
in the Hanalei Bay Watersheds
Matt Rosener
Hydrologist
Hanalei Watershed Hui
LocationLocation
Place of extraordinary natural beauty…
…steeped in cultural traditions
Hanalei Watershed Hui
• Small, non-profit conservation organization
• Working to protect the resources of Hanalei
• Do this by:
– Studying watersheds, identifying problems
– Planning for solutions & implementing them
– Education & outreach programs
Hanalei Bay Watersheds TMDL Study
• Draft TMDL completed Jan. ’07
• Tetra Tech was contractor
• Hanalei Watershed Hui did storm sampling
• DOH presented to community Feb. ’07
Following tables/graphics from the TMDL report
TMDLs and Load Targets for the
Hanalei Bay Watersheds
• Draft TMDLs developed for enterococcus and turbidity (linked to TSS)
• Draft Load Targets developed for nutrients (TP, TN, NH4, NOx)
~ 90% of land area is forest or scrub/shrub land cover
~ 90% of TSS and Enterococcous loads attributed to these areas
Are the Load Reduction Prescriptions Realistic?
• Possibly for Enterococcous, esp. if human source is dominant and effectively addressed
• Probably not for suspended sediment
• Why not?
0
2
4
6
8
10
12
14
16
18
24-hr rainfall total
2/15
/200
6
2/17
/200
6
2/19
/200
6
2/21
/200
6
2/23
/200
6
2/25
/200
6
2/27
/200
6
3/1/
2006
3/3/
2006
3/5/
2006
3/7/
2006
3/9/
2006
3/11
/200
6
3/13
/200
6
3/15
/200
6
3/17
/200
6
3/19
/200
6
3/21
/200
6
3/23
/200
6
3/25
/200
6
3/27
/200
6
3/29
/200
6
3/31
/200
6
Date
Hanalei Rainfall 15 February - 31 March 2006
Wai'ale'ale
Hanalei River
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
Beach Monitoring –Entero Stats 2003Beach Monitoring –Entero Stats 2003
Stream Monitoring –Entero Stats 2003Stream Monitoring –Entero Stats 2003
What are we doing about it?What are we doing about it?Hanalei Watershed BMPsHanalei Watershed BMPs
County cesspool & septic system County cesspool & septic system
up-grades at beach parksup-grades at beach parks
New Septic Systems Installed at County Facilities in Hanalei
• At Hanalei Baseyard on 2 March 2006
• At Pavilion (men’s) on 8 March 2006
• At Pavilion (women’s) on 9 March 2006
HWH replacing septic upgrades for homes in/near riparian areas
Hanalei River at Weke Rd - Entero Levels 2000-2008
0.0
50.0
100.0
150.0
200.0
250.0
300.0
2000 2001 2002 2003 2004 2005 2006 2007 2008
Year
Ente
ro G
eom
ean
(MPN
/100
mL)
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
Annual Geomean
Geomean Standard
% Time Over Standard
Hanalei Landing (Pier) - Entero Levels 2000-2008
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
2000 2001 2002 2003 2004 2005 2006 2007 2008
Year
Ente
ro G
eom
ean
(MPN
/100
mL)
0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
50%
Annual Geomean
Geomean Standard
% Time Over Standard
All waters turbidity-impaired
Trail Restoration
Next Steps
• Focused monitoring & source assessment
• Develop Watershed-based Action Plan
• Implement BMPs & monitor effectiveness
• Continue water quality research programs
Mahalo
TMDLs and Load Targets for the
Hanalei Bay Watersheds
• Draft TMDLs developed for enterococcus and turbidity (linked to TSS)
• Draft Load Targets developed for nutrients (TP, TN, NH4, NOx)
Technical Approach
• Developed a modeling framework to assess cause-effect relationship between source contributions and response of the river, estuary, and bay
• Tested/calibrated the model using available flow and water quality monitoring data at multiple locations
• Used model to determine source loads that enable river, estuary, and bay to achieve applicable water quality criteria at all times
Modeling Framework• Watershed model: EPA’s Loading Simulation Program in C++
(LSPC)– Watershed hydrology and flow in Hanalei River– Erosion from the land surface and mass transport in the river– Bacteria and nutrient loading from the land surface and transport
in the river
• Estuary and bay model: EPA’s Environmental Fluid Dynamics Code (EFDC)
– Freshwater inputs from watershed model used as boundary condition
– Fate and transport of bacteria, nutrients, and TSS in the Hanalei Estuary (tidal) and Hanalei Bay
– 1-dimensional representation of the estuary
– 2-dimensional representation of the bay