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

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USGS Gage Name

Time, Date

Stage
(feet)

Flow
(c.f.s.)

Flow Change
(c.f.s./hr)
North Fork Snoqualmie River (external link) 5:15 AM, 2/9/2010 2.57 154 0
Middle Fork Snoqualmie River (external link) 5:15 AM, 2/9/2010 1.77 347 -3
South Fork Snoqualmie River (external link) 5:15 AM, 2/9/2010 9.90 112 0
Sum of Snoqualmie River Forks 5:15 AM, 2/9/2010 n/a 613 -3
Snoqualmie River near Snoqualmie (external link) 5:30 AM, 2/9/2010 4.10 1040 +10
Snoqualmie River near Carnation (external link) 5:15 AM, 2/9/2010 46.37 1560 0
Snoqualmie River at Duvall (external link) 5:30 AM, 2/9/2010 28.88 n/a 0 (stage, in feet)

Notes:

This data was requested from USGS at 2/9/2010 6:02:38 AM.

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 5:15 AM on 2/9/2010 is 613.00 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.

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 154.00 c.f.s. at 5:15 AM (provisional)Middle Fork Snoqualmie River: Flow 347.00 c.f.s. at 5:15 AM (provisional)South Fork Snoqualmie River: Flow 112.00 c.f.s. at 5:15 AM (provisional)Sum of Snoqualmie River Forks: Flow 613.00 c.f.s. at 5:15 AM (provisional)Snoqualmie River near Snoqualmie: Flow 1040.00 c.f.s. at 5:30 AM (provisional)Snoqualmie River near Carnation: Flow 1560.00 c.f.s. at 5:15 AM (provisional)Snoqualmie River at Duvall: Flow c.f.s. at 5:30 AM (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 Threshhold (sum of the Forks) Description Roads that may overtop and close
1 6000 c.f.s. Internal Alert  
2 12000 c.f.s. Lowland flooding Neal Rd, SE Reinig Rd, West Snoqualmie River Rd NE (Walker Rd) Snoqualmie Meadowbrook Rd, Mill Pond Rd.
3 20000 c.f.s. Flooding of varied depths occurs in the entire Snoqualmie Valley Fall City -Carnation Rd, Tolt Hill Rd, Novelty Flats Rd.
4 38000 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 at Carnation
January 7-8, 2009 54,110 c.f.s. * 60,700 c.f.s. * 83,400 c.f.s. * 62.25 ft *
November 12-13, 2008 44,010 c.f.s. * 45,200 c.f.s. * 63,700 c.f.s. * 60.54 ft *
November 6-7, 2006 53,476 c.f.s. 55,000 c.f.s. 71,800 c.f.s. 61.28 ft
January 18-19, 2005 36,330 c.f.s. 37,100 c.f.s. 49,400 c.f.s. 59.08 ft
October 21, 2003 32,700 c.f.s. 29,200 c.f.s. 31,000 c.f.s. 56.83 ft
February, 1996 44,430 c.f.s. 51,700 c.f.s. 61,600 c.f.s. 60.34 ft
November, 1995 49,350 c.f.s. 50,200 c.f.s. 62,400 c.f.s. 60.30 ft
November, 1990 50,100 c.f.s. 78,800 c.f.s. 65,200 c.f.s. 60.70 ft

*provisional data

The U.S. Army Corps of Engineers also provides access to the provisional gage data:

North Fork Snoqualmie River (external link)
Middle Fork Snoqualmie River (external link)
South Fork Snoqualmie River (external link)
Snoqualmie River near Snoqualmie (external link)
Snoqualmie River near Carnation (external link)
Snoqualmie River at Duvall (external link)

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


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
Aerial photo comparison - 1995 flood vs normal conditions
Snoqualmie River Flood Reduction Project 205
Lower Tolt River Floodplain Restoration


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» Return to King County Flooding Services
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