Pump Station Revetment Improvements

Community engagement

All public, tribal, and partner comments and suggestions are welcome to help inform the design of the revetment improvement project. The project team will be at local events and visiting the neighborhood over the next year to hear from you. You can also reach out directly to the project contact at any time with questions or comments.

Project Overview

The King County Flood Control District, together with King County as service provider, is planning to make improvements to the damaged Pump Station Revetment on the left bank of the Snoqualmie River, directly upstream of Meadowbrook Bridge. Improving the revetment will help prevent potential erosion damage to sanitary sewer infrastructure and the historic Meadowbrook Bridge.

The project is located in the City of Snoqualmie along the left bank of the Snoqualmie River at River mile 40.3, directly upstream of the Meadowbrook Bridge and at the dead-end of SE Walnut Street.

Channel Erosion Study Underway:
To better understand what is causing changes to the riverbanks in this project area, the project is studying the impact of improvements made to Snoqualmie Falls from 2004 to 2012. In the 2016 Snoqualmie River Hydraulic Study, the County found that lowering the Snoqualmie Falls diversion weir and widening of the channel upstream of the Falls dropped flood levels by 3.8 feet during a 100-year flood (1% annual exceedance probability) at the Falls. These changes lowered the depth of flooding and the number of flood events in the City of Snoqualmie. This study will also help guide the design of the Pump Station repair. The study will be complete in late 2024.

What is a revetment?
Revetments are structures built along a riverbank to reduce erosion, usually built with rocks, wood, plants, and other materials. Although they limit bank erosion from river channel migration, revetments do not prevent flooding. There are many resources available to reduce flood risks and increased flood preparedness, at www.kingcounty.gov/prepareforflooding.

What is a weir?
Weirs are human-made or naturally occurring structures across a river. They can change the river’s water level height and can be used for power generation.

What is Annual Exceedance Probability (AEP)?
AEP is the chance, or probability, that flooding at a particular extent or level might occur or be exceeded in any given year. When you see 50% AEP, it means that there is a 50% chance that flooding at that level will occur or be exceeded each year. We used to talk about floods as a frequency interval (such as a 2-year flood) but that is misleading.

Project goals

• Repair a damaged rock revetment on the Snoqualmie River that protects Pump Station No. 4 from river erosion. This will prevent the river from getting behind the revetment and damaging the pump station and the downstream Meadowbrook Bridge.
• Characterize the Snoqualmie River channel’s response to adjustments made to the Snoqualmie Falls weir and channel between 2004 and 2012. The study will determine if erosion at this project location is related to those actions and if the river adjustment to those changes is continuing.
• Provide community organizations, partners, tribes, neighbors, and other interested parties with accurate and timely information in multiple formats and opportunities for project feedback and involvement.

Project schedule (subject to change)

Construction impacts

Project construction is currently scheduled for Summer or Fall 2027. There will be little or no impact to neighbors until construction begins. King County will work to reduce noise, dust, and traffic impacts on SE Walnut Street during construction.

King County is working to limit the impacts of construction. Construction may temporarily impact use of roads, sidewalks, trails, and parks in the area.

We will update this webpage with impacts to roads, sidewalks, trails, or parks in the area as the project moves through design and permitting. We will also post signs and flyers near the project site and notify local businesses and residents before and during construction. To receive updates, please sign up for the project email list.