TagMiller Creek(260)

Attachment C summarizing proposed mitigation actions to avoid and minimize wetland impacts for a runway project at Sea-Tac Airport area. Document details mitigation requirements and actions for Miller Creek, Des Moines Creek, Category II and III wetlands (Wetlands 3, 4, 5, 8, 9, 18, 37, 44, 52, A1, and Borrow Area wetlands B1, B4–B10, B15a,

Three bar charts showing 7-day low flow occurrences modeled using 1994 HSPF (Hydrological Simulation Program Fortran) for the period 1949-1995. Charts cover Miller Creek, Des Moines Creek, and Walker Creek, displaying occurrence counts (0-4) by date ranging from summer through winter months (June through December). AR034949-AR034951. Related to stormwater hydrology and low flow analysis for

This section of the Sea-Tac Airport Master Plan Update Environmental Impact Statement examines how proposed airport expansion alternatives would affect water quality and hydrology in the surrounding area, particularly Miller Creek and Des Moines Creek. The analysis finds that increased impervious surfaces would raise stormwater runoff volumes and peak flow rates, potentially causing downstream flooding and erosion, but that required detention storage facilities and mitigation measures would largely prevent significant water quality degradation. Both creeks, while classified as Class AA extraordinary waters, already show some pollution from urban stormwater runoff, though deeper regional groundwater used for drinking remains unaffected.

This figure from the Sea-Tac Airport Stormwater Management Plan maps current fish habitat in the Des Moines Creek, Miller Creek, and Walker Creek watersheds near Sea-Tac Airport. It identifies the fish species present in various streams and lakes in the area, including Coho, Cutthroat, Steelhead, Chum, Chinook, Bull Trout, and Pumpkinseed Sunfish. The map also highlights piped stream segments and areas of potential Chinook and Bull Trout habitat within these interconnected watershed basins adjacent to Puget Sound.

Joseph Brascher, a hydrologic modeling expert at Aqua Terra Consultants, submitted this declaration in a 2001 Washington State Pollution Control Hearings Board case involving the Port of Seattle's Master Plan Update for Sea-Tac International Airport. He describes how the HSPF (Hydrologic Simulation Program – Fortran) computer model was used to analyze stormwater runoff and flow impacts on Miller and Walker Creeks resulting from planned airport construction. The declaration also outlines additional studies and design details requested by the Washington State Department of Ecology as conditions of its §401 water quality certification for the project.

Exhibit 175 (AR018443) summarizes wetland mitigation credit for Sea-Tac Airport Master Plan Update improvements. Tables detail in-basin mitigation (102.27 acres, 29.80 credit) and out-of-basin mitigation (65.38 acres, 42.91 credit) for a total of 167.65 acres and 72.71 mitigation credits. Specific mitigation sites include Vacca Farm, Miller Creek Wetland and Riparian Buffer, Tyee Valley Golf Course,

Exhibit AR018442 is a detailed map of wetland and stream impacts in the Miller Creek Basin associated with the Seattle-Tacoma International Airport Third Runway project. The map shows delineated wetlands verified by the Army Corps of Engineers (ACOE), wetlands not verified by ACOE, water features, Third Runway embankment, Runway Safety Areas (RSAs), relocated S 154th

Prefiled direct testimony of Jan L. Cassin, Ph.D., submitted in Pollution Control Hearings Board (PCHB) case No. 01-160, Airport Communities Coalition (ACC) and Citizens Against Sea-Tac Expansion (CASE) v. Department of Ecology and Port Of Seattle. Testimony addresses wetlands identification on the Vacca Farm site, mitigation plan adequacy, restoration and enhancement credit ratios, Miller Creek

Prefiled testimony of Joseph Brascher submitted in Pollution Control Hearings Board (PCHB) case No. 01-160, Airport Communities Coalition (ACC) and Citizens Against Sea-Tac Expansion (CASE) v. State of Washington Department of Ecology and Port Of Seattle. Testimony covers low streamflow modeling at Seattle-Tacoma International Airport (STIA) using HSPF (Hydrological Simulation Program Fortran) model integrated with

This declaration by stormwater engineer Paul S. Fendt, filed in a Washington State Pollution Control Hearings Board case, explains how Sea-Tac International Airport's Master Plan Update will increase impervious surfaces and alter stormwater runoff into Miller, Walker, and Des Moines Creeks. The document outlines mitigation measures, including 344.1 acre-feet of new detention storage and controlled low-flow water releases, to offset increased peak flows and reduced summer stream flows caused by airport expansion. It provides technical background on the affected watersheds and the Port of Seattle's stormwater management strategy.