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Flooding Services

King County, Washington

Snoqualmie River Flooding Information
USGS gage data, map, alert phases, and recent high flows

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USGS Gage Name

Time, Date



Flow Change

North Fork Snoqualmie River (external link) 6:15 PM, 9/1/2014 2.02 78 0
Middle Fork Snoqualmie River (external link) 6:15 PM, 9/1/2014 1.89 315 +5
South Fork Snoqualmie River (external link) 6:15 PM, 9/1/2014 9.97 99 0
Sum of Snoqualmie River Forks 6:15 PM, 9/1/2014 n/a 492 +5
Snoqualmie River near Snoqualmie (external link) 6:30 PM, 9/1/2014 3.77 808 0
Snoqualmie River near Carnation (external link) 6:15 PM, 9/1/2014 45.80 1190 -10
Snoqualmie River at Duvall (external link) 6:00 PM, 9/1/2014 28.89 n/a 0 (stage, in feet)


This data was requested from USGS at 9/1/2014 6:42:17 PM.

The next request for USGS data is expected in approximately 3 minutes from when this page was loaded.

The flood phases of the Snoqualmie River are based on the sum of flow for the North, Middle and South forks. The sum of the Forks as of 6:15 PM on 9/1/2014 is 492.00 c.f.s. (cubic feet per second) based on USGS provisional data. The sum of the forks represents the most recent flows available from three independent gages providing the best available flood warning information. If a gage has an older sampling time than others, its most recent measurement is used in calculating the sum of the forks.

c.f.s. = cubic feet per second.
King County provides funding to the United States Geological Survey (USGS) to support the operation and maintenance of river and stream gages and related systems. The term "gage" is defined as an instrument for measuring or testing. USGS uses the term "streamgage" to describe their equipment that obtains estimates of the amount of water flowing in streams and rivers. More information about USGS streamgages

North Fork Snoqualmie River: Flow 78.00 c.f.s. at 6:15 PM (provisional)Middle Fork Snoqualmie River: Flow 315.00 c.f.s. at 6:15 PM (provisional)South Fork Snoqualmie River: Flow 99.00 c.f.s. at 6:15 PM (provisional)Sum of Snoqualmie River Forks: Flow 492.00 c.f.s. at 6:15 PM (provisional)Snoqualmie River near Snoqualmie: Flow 808.00 c.f.s. at 6:30 PM (provisional)Snoqualmie River near Carnation: Flow 1190.00 c.f.s. at 6:15 PM (provisional)Snoqualmie River at Duvall: Stage 28.89 ft. at 6:00 PM (provisional)Click to view flooding information for the Raging RiverClick to view flood information for the Tolt RiverClick to view flooding information for the Skykomish River
Snoqualmie River Flood Phases
Phase Phase Threshold (sum of the Forks) Description Roads that may overtop and close
1 6,000 c.f.s. Internal Alert  
2 12,000 c.f.s. Lowland flooding Neal Rd, SE Reinig Rd, West Snoqualmie River Rd NE (Walker Rd) Snoqualmie Meadowbrook Rd, Mill Pond Rd.
3 20,000 c.f.s. Flooding of varied depths occurs in the entire Snoqualmie Valley Fall City -Carnation Rd, Tolt Hill Rd, NE 124th St.
4 38,000 c.f.s. Some residential areas may experience dangerous high velocities and flooding of homes. Woodinville-Duvall Rd, SR 203 between Duvall and Carnation, Moon Valley Rd, South Fork Rd

Snoqualmie River gages map - flooding
Recent High Flow Data
High Flow Event Sum of the Forks Snoqualmie River near Snoqualmie Snoqualmie River near Carnation
January 16-17, 2011 34,740 c.f.s. 37,900 c.f.s. 51,600 c.f.s. 59.32 ft
January 7-8, 2009 54,110 c.f.s. 60,700 c.f.s. 82,900 c.f.s. 62.21 ft
November 6-7, 2006 53,500 c.f.s. 55,000 c.f.s. 71,800 c.f.s. 61.28 ft
February, 1996 43,740 c.f.s. 51,700 c.f.s. 61,600 c.f.s. 60.34 ft
November, 1995 47,960 c.f.s. 50,200 c.f.s. 62,400 c.f.s. 60.30 ft
November, 1990 48,250 c.f.s. 78,800 c.f.s. 65,200 c.f.s. 60.70 ft

Snohomish County Flood Warning Information (external link), 425-388-5060

The National Weather Service also provides access to provisional gage data:

Snoqualmie River near the Falls (external link)

Snoqualmie River near Carnation (external link)

More Snoqualmie Valley Flood Documentation

Flood Photo Viewer

Video of the Election Day Flood, November, 2006:

Photos of phase 4 flood, November, 2006
Aerial photos of phase 4 flood, December, 1995
Snoqualmie River Flood Reduction Project 205
Lower Tolt River Floodplain Restoration

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