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Water and Land Resources Division

King County, Washington

For questions about the Water and Land Resources' website, please contact Fred Bentler, webmaster.

Water and Land Resources Division, King County, Washington

River and Floodplain Management Section

Lower Snoqualmie Valley farmers take our survey about flooding

The King County Flood Control District is initiating a survey of farmers in the lower Snoqualmie Valley to learn more about how flooding impacts agricultural operations and ultimately help set priorities for implementing actions such as farm pads and raising houses and barns above flood levels.

This section is responsible for carrying out flood risk reduction projects and programs to protect public safety along King County's major rivers. The work of this section is funded by the King County Flood Control District which was established in April, 2007 by the Metropolitan King County Council to protect public health and safety, regional economic centers, public and private properties and transportation corridors.

In the News

Green River System-Wide Improvement Framework (SWIF) - Public meetings scheduled for Sept. 23 and 30.
South Fork Snoqualmie River Corridor Plan - Public meeting schedule for Oct. 15.
Lower Snoqualmie Valley Farmers Survey
Lower White River Countyline reach projects (White River)
Rainbow Bend Floodplain Reconnection project (Cedar River)
Reddington Levee Setback project (Green River)


Capital Improvement Projects
Projects are designed to reduce risks to public health and safety, protect infrastructure and provide habitat components in compliance with natural resource regulations.

Levees and Revetments
Over 500 levees and revetments exist along King County rivers. Inspections and maintenance occur regularly on these river facilities.


Flood Warning System
The system is designed to warn and provide information to residents and agencies about impending floodwaters on major rivers so they can take action and prepare themselves before serious flooding occurs. The web site links to real-time river gage data and describes the local flooding homeowners can expect at different flood phases based on past flood events.

Home Buyouts and Elevations in flood prone areas
The home elevation program assists property owners with the costs of raising the finished floor of a home above the 100-year elevation, substantially reducing the threat of future damage. Home buyouts provide a permanent solution to the risks and damages of repetitive flooding.

Known Hazards in King County Rivers
Information about known hazards on the rivers of King County including maps and photos of projects containing large wood.

Grants Program
Grants from a variety of sources are pursued to fund flood hazard reduction projects and programmatic activities that mitigate flooding problems throughout the county.

River Planning
This program element includes ongoing activities and special studies related to river corridor management, ecologically guided floodplain restoration, public safety, and flood hazard reduction.


2013 King County Flood Hazard Management Plan Update and Progress Report
(Adopted Nov. 2013) The 2013 Flood Plan is a companion document to the 2006 King County Flood Hazard Management Plan, updating technical information and summarizing accomplishments since 2007. 

Floodplain Mapping and Channel Migration Hazard Mapping
Flood and channel migration hazard areas are identified and mapped. These hazard areas are regulated to limit or prevent at-risk development. Since 1991, updated flood boundaries have been mapped on nearly 80 miles of river, and channel migration zones along 46 miles of river.

Biological Effects Analysis Report
Published in October 2003 to determine the potential effects of the King County River Management Program on endangered, threatened, and candidate salmonids. Based on the results of this analysis, the County could decide if any elements of the River Management Program might require modification to come into compliance with the Endangered Species Act (ESA).

Guidelines for Bank Stabilization Projects: in the Riverine Environments of King County
Published in June 1993 to assist scientists and engineers with the design of bank stabilization projects for river and streambank protection. The Guidelines document is a practical guide for assessing erosion problems, evaluating alternative solutions and designing and constructing a bank stabilization project.


Green River Flood Control Zone District
The Green River Flood Control Zone District sunsetted at the end of 2007. The District was an interjurisdictional flood hazard reduction and resource management program that includes the operation, maintenance and repair of flood protection facilities and pump station on the lower Green River. It was replaced by the King County Flood Control District.

Snoqualmie River 205 Project
This project was designed to reduce flood elevations in and around the City of Snoqualmie.