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This interactive map demonstrates a variety of flood levels along the Cedar River to provide an increased awareness of potential flood conditions before a flood event occurs.

PLEASE NOTE: The flood inundations illustrated are derived from hydraulic modeling for specific flow levels. The river flows below correspond to the USGS gage data near Landsburg (external link). Flood phases are based on King County’s Flood warning and alerts for the Cedar River. The 2%, 1%, and 0.2% annual chance flows correspond to what has historically been termed the 50-year, 100-year, and 500-year flows. The extents and depths shown are approximate and should not be used for permitting or other regulatory purposes. While some flows used here are the same as those used to create the Flood Insurance Rate Maps (FIRMs) published by FEMA, these illustrations are not a substitute for using the FIRMs themselves.

Click on the map to see water depth for that location.
To view street or aerial basemap, use slider to set transparency for the flow layers
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Select a King County Flood Phase:
1,800 c.f.s. (Phase 1)
2,800 c.f.s. (Phase 2)
4,200 c.f.s. (Phase 3)
5,000 c.f.s. (Phase 4)

Select a recent peak flow:
6,580 c.f.s. (Similar to Nov. 30, 1995)
7,870 c.f.s. (Similar to Jan. 8, 2009)

Select a sample flow with a chance of happening in a given interval:
8,350 c.f.s. (2% annual = 50 year flow)
9,325 c.f.s. (Between 50 and 100 year flow)
10,300 c.f.s. (1% annual chance = 100 year flow)
16,100 c.f.s. (0.2% annual chance = 500 year flow)

c.f.s. = Cubic Feet per Second – A measure of the volume of water (in cubic feet) that flows past a specific river location each second.)

Disclaimer: The information provided in this interactive map has been complied by King County staff from a variety of sources, which are not static in nature, and so the information is subject to change without notice.  King County makes no representations or warranties, express or implied, as to the accuracy, completeness, timeliness, or rights to the use of such information.  King County shall not be liable for any errors, omissions, or inaccuracies in such information, regardless of their cause, and King County shall not be liable for any decision made, action taken, or action not taken by the user in reliance upon such information.  King County shall not be liable for any general, special, incidental, or consequential damages including, but not limited to, lost revenues or lost profits resulting from the use or misuse of the information gathered through the use of this interactive map.  This interactive map is not intended for use as a survey product or to generate documents of a legal nature.  Any sale of products or information generated through the use of this interactive map is prohibited except by written permission of King County.  This disclaimer is also made by the King County Flood Control District.

For more information about Cedar River flood levels and flows, please contact Ken Zweig, River and Floodplain Management Section.