IFS: 6014 – Honokōhau Stream, Maui
Instream Flow Standard: Hydrologic Unit of Honokōhau (6014)
Instream Flow Standard
CFS
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MGD
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Location / Notes
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---|---|---|
Natural flow | Natural flow | Kaluanui Stream, Natural flow below abandoned Honokōhau Ditch diversion. |
13.31 | 8.6 | Phase One: The interim IFS on Honokōhau Stream at McDonald’s Dam (at the 340 foot elevation), shall be a flow of 8.6 mgd. The interim IFS represents the restoration of 64% of median base flow (BFQ50) as estimated at USGS 16620000 (7.4 mgd), plus the additional 2.3 mgd of groundwater gains between USGS 16620000 and Aotaki Weir and 1.4 mgd of groundwater gains between Aotaki Weir and McDonald’s Dam minus 2.5 mgd for the Maui DWS. The interim IFS is expected to be in excess of the water needs to support the existing needs of lo‘i as well as future acreage while protecting aquatic biota, recreation, and domestic uses at all elevations, and ensuring sufficient water to meet traditional and customary practices 100% of the time in Honokōhau Valley. MLP is required to meet the interim IFS 100% of the time. There should also be adequate ditch flow to meet Maui DWS needs of 2.5 mgd at the Māhinahina WTF 100% of the time. It is understood that during extreme drought (< Q90; < 11.0 mgd at Aotaki Weir), 100% of the off-stream needs of non-public trust uses may not be met. |
Variable (at Q50 to at Q90) |
Variable (10.4 at Q50 to 6.8 at Q90) |
Phase 2 (upon initial DHHL implementation of Regional Plan): The interim IFS on Honokōhau Stream at McDonald’s Dam (at the 340 foot elevation), shall be a variable interim IFS (See Table 2 below). The interim IFS will be the restoration of 50% of total flow at USGS 16620000 plus 2.4 mgd in groundwater gained between USGS 16620000 and McDonald’s Dam. The 2.4 mgd is 50% of the estimated 4.8 mgd in total groundwater gain between USGS 16620000 and McDonald’s Dam. The interim IFS is expected to support all instream values and Honokōhau Valley domestic uses while providing for non-instream public trust uses (domestic uses provided by Maui DWS and DHHL). MLP is required to meet the interim IFS 100% of the time. There should also be adequate ditch flow to meet Maui DWS needs of 2.5 mgd at the Māhinahina WTF 100% of the time. With 2.0 mgd of non-potable agricultural water for DHHL, Maui DEM can blend 2.1 mgd of R1 water from the Lahaina Wastewater Treatment Facility at 50:50 to make available 4.2 mgd of non-potable water to meet the agricultural needs of DHHL and other agricultural uses in the Lahaina Region. It is understood that during extreme drought (< Q90; < 11.0 mgd at Aotaki Weir), 100% of the off-stream needs of non-public trust uses may not be met. However, Kapalua Water Company (KWC) has plenty of capacity in its drilled wells to utilize groundwater as a backup supply for its non-potable needs when insufficient water is available in the ditch. |
Gaging
Information Updates
Date
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Action
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Oct. 19, 2021 |
Commission on Water Resource Management Meeting (View virtual Meeting on Vimeo)
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May 18, 2021 |
Commission on Water Resource Management Meeting (View virtual Meeting on Vimeo)
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Apr. 20, 2021 |
Commission on Water Resource Management Meeting (View virtual Meeting on Vimeo)
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Sep. 15, 2020 |
Commission on Water Resource Management Meeting (View virtual Meeting on Vimeo)
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Nov. 20, 2019 |
Commission on Water Resource Management Meeting
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References
- Cheng, C.L., 2014, Low-flow characteristics of streams in the Lahaina District, West Maui, Hawaiʻi: U.S. Geological Survey Scientific Investigations Report 2014–5087, 58 p., https://dx.doi.org/10.3133/sir20145087.
- Engott, John A., and Vana, Thomas T. 2007, Effects of agricultural land-use changes and rainfall on ground-water recharge in central and west Maui, Hawaii, 1926-2004: U.S. Geological Survey Scientific Investigations Report 2007-5103, 56 p., https://pubs.usgs.gov/sir/2007/5103/.
- Fontaine, R.A., 2003, Availability and Distribution of Base Flow in Lower Honokohau Stream, Island of Maui, Hawaii: U.S. Geological Survey Water-Resources Investigations Report 03-4060, 44 p., https://pubs.usgs.gov/wri/wri034060/.
- Gingerich, S.B., and Engott, J.A., 2012, Groundwater availability in the Lahaina District, west Maui, Hawaiʻi: U.S. Geological Survey Scientific Investigations Report 2012–5010, 90 p., https://pubs.usgs.gov/sir/2012/5010/.
- Johnson, A.G., Engott, J.A., Bassiouni, Maoya, and Rotzoll, Kolja, 2018, Spatially distributed groundwater recharge estimated using a water-budget model for the Island of Maui, Hawai`i, 1978–2007 (ver. 2.0, February 2018): U.S. Geological Survey Scientific Investigations Report 2014–5168, 53 p., https://doi.org/10.3133/sir20145168.
- Shade, Patricia J., 1996, Water Budget for the Lahaina District, Island of Maui, Hawaii: U.S. Geological Survey Water-Resources Investigations Report 96-4238, 27 p., https://doi.org/10.3133/wri964238.