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