Report of the Joint Task Force: Instream Flow Needs Analysis for Northern New Castle County, Delaware
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1997-01-31
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Abstract
The Instream Flow Needs Analysis for Northern New Castle County, Phase Two: 7Q10 Assessment, was incorporated into the Phase One Final Report approved by the Joint Task Force in 1995, with refinements added in 1996. Phase Two was funded following concerns from the Delaware Department of Natural Resources and Environmental Control about using a general approach to target fish species in the Phase One assessment. The second phase aimed to provide more detailed data on habitat suitability and water quality, particularly through the development of a wetted perimeter analysis to assess the impact of a 7Q10 passby requirement on public water purveyors. Despite a delay, Michael Stangl, a fisheries biologist, conducted stream habitat and fisheries investigations during the 1995 drought, providing valuable data that helped refine the target species for Phase Two. The study concluded that the Longnose Dace was the key target species for both the Brandywine and White Clay creeks.
Collaborators, including Richard Greene and Gerald Kauffman, contributed to the wetted perimeter analysis, confirming that habitat flow depth and velocity in the riffle areas would meet the 7Q10 conditions. The Task Force concluded that a 7Q10 minimum flow standard for withdrawals over 50,000 gallons per day would protect aquatic habitat, water quality, and salt front maintenance in Northern New Castle County. The report recommended supplemental water supplies through interconnections with neighboring systems during drought conditions and identified the Churchman’s Marsh Environmental Impact Statement process as the next step in determining new water sources. A water resources management plan for the Christina River Basin was also advised to ensure coordinated public and private water supply operations in the region.