Notes
Letter dated July 23, 2001 from Port Of Seattle to Ann E. Kenny at Washington State Department of Ecology Northwest Regional Office regarding Low Streamflow Analysis and Summer Low Flow Impact Offset Facility Proposal for Seattle-Tacoma International Airport. Covers summer low streamflow impacts in Des Moines Creek, Miller Creek, and Walker Creek from airport Master Plan Update projects. Proposes underground vault detention of stormwater for release during summer low flow periods (July 24–October 24 for Des Moines Creek; August 1–October 31 for Miller and Walker Creeks). Documents 2-year 7-day low flows (Des Moines Creek 0.35 cfs, Miller Creek 0.74 cfs, Walker Creek 0.79 cfs), Port impacts (0.10, 0.13, 0.09 cfs respectively), and vault sizes (12.2, 18.8, 15.0 acre-feet). Methodology uses HSPF models, 1949–1995 period of record, 1994 and 2006 land use conditions, salmonid biology consultation, 401 permit, King County, Floyd Snider McCarthy. AR 029214.