Notes
Memorandum dated August 7, 2001 from Dave Garland, NWRO Water Quality Watershed Unit Supervisor, to Ann Kenny, Kevin Fitzpatrick, and Ray Hellwig of the Washington State Department of Ecology Northwest Regional Office. Reviews the Parametrix Inc. July 2001 report ‘Low Flow Analysis, Flow Impact Offset Facility Proposal’ prepared for Port Of Seattle regarding predicted impacts of the proposed third runway on late summer streamflows in Miller Creek, Walker Creek, and Des Moines Creek. References Pacific Groundwater Group ‘slice model’ (PGG, June 2000), EarthTech December 2000 Sea-Tac Airport Master Plan Update Low Streamflow Analysis, King County DNR August 3, 2001 review comments, and HSPF streamflow models. Discusses 3-month low-flow augmentation period, embankment drainage, fill thickness, stormwater storage and release facilities, and non-hydrologic impacts including water rights and water district water. Net streamflow reductions for Miller Creek estimated at -0.02 cfs and Walker Creek at -0.01 cfs (July 2001). AR 017883, Exhibit 108.