King County Flood Warning System

National Weather Service: Current Flood Watches, Warnings and Statements

Important phone numbers and web links

Map of River Basins in King County

King County provides funding to the United States Geological Survey to support the operation and maintenance of river and stream gages and related systems.

What is the purpose of the King County Flood Warning Program?

To warn residents and agencies of impending floodwaters on major rivers so they can take action and prepare themselves before serious flooding occurs. In most locations, the warning system provides at least 2 hours lead time before floodwaters reach damaging levels. This program does not take the place of individuals and local groups making their own flood disaster plans.

When does flooding and high water typically happen in King County?

Most commonly from November through February during periods of heavy rainfall or rapid snowmelt. Historically, King County rivers have flooded in every month but August.

How does the Flood Warning System operate?

When high water conditions are imminent, King County activates its Flood Warning Center. Operation of the Center is based on a four-phase warning system, issued independently for each river. The thresholds for each phase are based on river gages which measure the flow and stage (depth) of the major rivers in various locations. King County staff monitor the gages on a 24 hour basis, so that actions can be taken depending on river conditions.

What other information is available from the Flood Warning Center?

King County (KC) works closely with the National Weather Service to obtain forecast information used to make flood predictions. Close coordination occurs with the KC Office of Emergency Management, KC Roads, and other agencies to obtain up-to-date information about problems sites, road closures, evacuations and other emergency services. Coordination also occurs with the U.S. Army Corps of Engineers and Seattle Public Utilities regarding dam operations. Personnel at the Center are available to answer questions and help interpret gage readings during a flood event. The number is 206-296-4535 or 800-768-7932.

What can you do to avoid flood disasters?

Once a warning is issued by the National Weather Service or by King County, residents should prepare for flooding. Becoming familiar with the relationship between upstream gage readings and local flood characteristics can help you prepare your individual emergency plan. Read what you can do before, during and after a flood. Residents should keep informed of changing river conditions and make early preparations in case of major flooding.

Where do I get sandbags?

As resources permit, King County may make sandbags available to property owners for pick up in public locations, such as fire stations and roadsides (call the Flood Warning Center for details 206-296-4535 or 800-768-7932). However, property owners should not rely on King County to provide these materials, as County supplies can be overwhelmed by demand. Some cities are also able to provide sand and sandbags for flood protection to their residents. Citizens are encouraged to prepare for flooding by buying sand and sandbags from a vendor.

What does each Phase mean?

At Phase I, County personnel are put on alert and preparations are made to open the Flood Warning Center. When a Phase II threshold is reached, the Center is opened. Staff at the Center monitor river gages and flood conditions around the clock, and gage information is updated hourly on a recorded message (call 206-296-8200 or 800-945-9263). When a Phase III threshold is reached, investigation crews are sent out to monitor flood control facilities (such as levees). Phase II-IV warnings are issued to police, fire departments, schools, other agencies, and the public through news media and in some neighborhoods through volunteer telephone trees.

For questions about the King County Flood Warning System, please contact Ken Zweig, River and Floodplain Management Unit.