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Snoqualmie River Flooding Information
USGS gage data, map, alert phases, and historical flood levels

Snoqualmie River gage map - flooding

USGS Gage Name

Time, Date



Flow Change

North Fork Snoqualmie River (external link)

12:30 PM, 2/17




Middle Fork Snoqualmie River (external link)

12:30 PM, 2/17




South Fork Snoqualmie River (external link)

12:30 PM, 2/17




Sum of the Forks

12:30 PM, 2/17




Snoqualmie River near Snoqualmie, WA (external link)

2:30 PM, 2/17




Snoqualmie River near Carnation, WA (external link)

2:00 PM, 2/17




Snoqualmie River near Duvall, WA (external link)

12:00 PM, 2/17





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 12:30 PM on 2/17/2004 is 1189 c.f.s. (cubic feet per second) based on USGS provisional data (external link).

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 to support the operation and maintenance of river and stream gages and related systems.

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, Woodinville-Carnation Rd, Moon Valley Rd, South Fork Rd

Historic Flood Peak Summary: recent high flows for reference
High Flow Event Sum of the Forks Snoqualmie River near Snoqualmie Snoqualmie River at Carnation

November, 1990

50,100 c.f.s.

78,800 c.f.s.

65,200 c.f.s.

60.70 ft

November, 1995

49,350 c.f.s.

50,200 c.f.s.

62,400 c.f.s.

60.30 ft

February, 1996

44,430 c.f.s.

51,700 c.f.s.

61,600 c.f.s.

60.34 ft

October 21, 2003
Provisional Data

32,700 c.f.s.

29,200 c.f.s.

31,000 c.f.s.

56.83 ft

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)

More Snoqualmie Valley Flood Information

Aerial photos of phase 4 flood, December, 1995
Aerial photo comparison - 1995 flood vs normal conditions (Internet Explorer Only)
Water Year 1996 Technical Flood Summary Report
Water Year 1997 Technical Flood Summary Report
Snoqualmie River Flood Reduction Project

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