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Snoqualmie River Flooding Information

USGS gage data, map, alert phases, and recent high flows

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New: Click on a gage name for graph and additional data.

USGS Gage Name

Time, Date

Stage
(feet)

Flow
(cfs)

Flow Change
(cfs/hr)

North Fork Snoqualmie River 11:15 AM, 5/31/2023 3.20 383 -8
Middle Fork Snoqualmie River 7:15 AM, 5/31/2023 3.58 1,210 0
South Fork Snoqualmie River 11:15 AM, 5/31/2023 11.24 347 -4
Sum of Snoqualmie River Forks 7:15 AM, 5/31/2023 n/a 1,940 n/a
Snoqualmie River near Snoqualmie 10:30 AM, 5/31/2023 5.71 2,590 -10
Snoqualmie River near Carnation 11:15 AM, 5/31/2023 46.44 n/a n/a
Snoqualmie River at Duvall 10:30 AM, 5/31/2023 22.78 n/a -0.02 (stage, in feet)

* Gage data currently unavailable.

** Sum currently unavailable.

Notes:

This data was requested from USGS at 5/31/2023 11:25:05 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 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. Flood phases remain in effect after flows decrease below designated thresholds until the river crests at the Carnation gage.

Snoqualmie River near Carnation real-time provisional data greater than 9,000 cfs (gage heights greater than about 50 ft) are not reliable due to unsteady flow conditions during high flows. Under these conditions, a loop stage-discharge rating exists such that the true discharge is generally greater than indicated on a rising hydrograph and less than indicated on a falling hydrograph. Corrections are applied following a high-flow event but data remain provisional until approved.

cfs = 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

Chart of recent / forecast data

Snoqualmie River Flood Phases
Phase Phase Threshold (sum of the Forks)    Description    Condition
1 6,000 cfs Internal Alert  
2 12,000 cfs Minor Flooding Roads that may overtop include Neal Road SE, Reinig Road, West Snoqualmie River Road NE (Walker Road), Snoqualmie Meadowbrook Road, and Mill Pond Road.
3 20,000 cfs Moderate Flooding Flooding of varied depths may occur across the entire Snoqualmie Valley. Roads that may overtop include Fall City-Carnation Road, West Snoqualmie River Rd SE between SE 24th St and NE Tolt Hill Rd, NE Tolt Hill Road, and Novelty Flats Road.
4 38,000 cfs Severe Flooding Some residential areas may experience dangerously high velocities and flooding of homes. Roads that may overtop include SE Reinig Road, Moon Valley Road, SE Fish Hatchery Rd, SE David Powell Rd, NE 124th Street, and Woodinville-Duvall Road
Snoqualmie River gages map - flooding
Recent High Flow Data
High Flow Event Sum of the Forks Snoqualmie River near Snoqualmie Snoqualmie River near Carnation
October 22, 2019 45,680 cfs 45,000 cfs 39,200 cfs 58.11 ft
December 9, 2015 41,120 cfs 49,500 cfs 56,200 cfs 59.78 ft
November 17-18, 2015 42,700 cfs 48,000 cfs 46,600 cfs 58.85 ft
January 5-6, 2015 44,210 cfs 50,100 cfs 53,900 cfs 59.24 ft
January 7-8, 2009 54,110 cfs 60,700 cfs 82,900 cfs 62.21 ft
November 6-7, 2006 53,500 cfs 55,000 cfs 71,800 cfs 61.28 ft
February, 1996 43,740 cfs 51,700 cfs 61,600 cfs 60.34 ft
November, 1995 47,960 cfs 50,200 cfs 62,400 cfs 60.30 ft
November, 1990 48,250 cfs 74,300 cfs 65,200 cfs 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)

Other Flood-related Information

» Historical flood photos
» Return to the The Flood Warning System Page
» Return to King County Flooding Services
» See other Snoqualmie Basin Topics