Snoqualmie Flood Reduction Project
also known as Snoqualmie 205 Project)

The Snoqualmie Flood Reduction Project is a proposal to lower flood depths in and around the City of Snoqualmie. The "205 Project" name is a reference to the federal law that allows and funds the U.S. Army Corps of Engineers to participate in this type of project. The project is under construction at this time. Construction status June 10, 2004 (827KB PDF)
This air photo shows the historic City of Snoqualmie. The Snoqualmie River flows through town, from the right hand side of this picture to the upper left corner. The blue lines on this image represent the 100-year floodplain boundary. This floodplain is shaped as a classic "bottleneck", where the narrow rocky river channel above Snoqualmie Falls causes deep and broad flooding in the upstream community. For this reason, the 205 project would concentrate on the narrow channel to help reduce flood depths and damages upstream.
The Snoqualmie Flood Reduction Project has three major elements, which are: Rock excavation along the right bank (looking downstream), just upstream of the hydroelectric intake Earth excavation along the left bank, just downstream of the SR 202 bridge Removal of a partially-failed railroad bridge
This image shows the major project elements along the Snoqualmie River channel in the City of Snoqualmie. The river flows generally to the Northwest. Snoqualmie Falls and its plunge pool are visible in the upper-left corner. Also visible: Fall City-Snoqualmie Road (SR 202) bridge across the river, and new Snoqualmie Parkway (still under construction in this 1996 photo).
The outlines on this air photo show the proposed limit of project excavation. The photo shows Snoqualmie Falls and its plunge pool at the upper left corner. The Salish Lodge is near the top center of the photo, and the SR 202 bridge is at the lower right. As shown, the excavation would extend to nearly the middle of the river channel.

The following documents describe many of the project details, as well as the needs for which the project is designed. These documents were developed for the County Council approval process, which was completed in July of 2002. (Adobe Acrobat).

1. Transmittal Letter from Executive Sims to council

2. WLRD Presentation to council in support of Executive proposal (2.8 Mg)

3. Council Staff Report

4. Council Motion (project approval)

The Corps of Engineers and the City of Snoqualmie have entered agreements with King County that specify agency roles and responsibilities for completion of this project. Following are those agency agreements.

1. Contract with Corps of Engineers

2. Contract with City

3. Project Management Plan

All of the required permits have been approved, and the Corps has advertised the project in two seperate construction contracts to prospective bidders. The first contract is for channel excavation, and the second is for bridge removal. Both of the Corps solicitations are available on-line and include the complete construction plans and specifications. Following is an excerpt of selected plan sheets in .pdf format, as well as links for the complete solicitation on the Corps web page.

1. Selected plan sheets (3.0 Mg)

2. Corps solicitation for channel excavation contractor (removed 12/09)

3. Corps solicitation for bridge removal contractor (removed 12/09)

4. On Screen Takeoff software for viewing plan sheets in Corps solicitation

The project is expected to reduce the depth and frequency of flooding in Snoqualmie, where more than 600 homes and most of the commercial area are subject to severe flood damages. The Corps estimates that the project will prevent more than half of the economic damages caused by this flood problem, with an average annual savings of $837,000. Total project cost is estimated at $7.65 million, of which the Corps will fund $4.40 million (58%).

Because the project will move flood water through the Snoqualmie area more readily, it may have a small adverse impact on downstream flood problems. This relationship was studied in detail by the Corps of Engineers. Their calculations show that downstream flooding may become as much as 0.1 foot deeper at the peak of a 100-year flood. Impacts would be smaller during lesser (more frequent) floods, and would diminish with distance from Snoqualmie. Still, this adverse impact is enough that the project includes a Downstream Assistance Program (DAP) that can help to address flood problems where this impact would occur.

The Snoqualmie Flood Reduction Project is proposed by the U.S. Army Corps of Engineers. King County and the City of Snoqualmie share the local sponsorship responsibilities for this Corps of Engineers project. Staff contacts at the three agencies are:

Tim Shaw, Project Manager, U.S. Army Corps of Engineers, 206-764-6978, timothy.m.shaw@usace.army.mil

Kirk Holmes, Public Works Director, City of Snoqualmie, 425-831-4919 ext. 12, kholmes@ci.snoqualmie.wa.us

Tom Bean, Senior Engineer, King County River and Floodplain Management Section, 206-296-8377.

For questions about the Snoqualmie 205 Project, please contact Tom Bean, Senior Engineer, River and Floodplain Management Section.