Flood Event Report for March 23-27, 2025 - King County Flood Control District

Issued by the King County Flood Control District on April 2, 2025

This report provides an after-action analysis of the flood event that occurred in King County from March 23 to March 27, 2025. The flood primarily affected the Snoqualmie River Basin, taking the basin into Flood Phase 2 on two occasions. The Tolt River, South Fork Skykomish River, Green River, and Cedar River also entered Flood Phase 1. This report provides a summary, response overview, communications summary, a look at infrastructure and critical facilities, lessons learned, and recognitions.

Flood Event Summary

Snoqualmie River Basin

On Sunday, March 23, Flood Phase 1 was initiated at 7:15 p.m. when 6,149 cfs was observed by King County’s “Sum of Snoqualmie River Forks” river flow data chart. Flow is measured in cubic feet per second (cfs). At 11:15 p.m. on Sunday, March 23, the Sum of the Snoqualmie River Forks data measured 12,150 cfs, triggering a Flood Phase 2 stage.

Chart of flow data for the Sum of the Snoqualmie River Forks for the March 23-27 flood event

In the early morning hours of Monday, March 24, King County activated the Flood Warning Center at 12:45 a.m. and issued a public notification to the media at 1:33 a.m. The Flood Warning Center remained open until 7:45 a.m. on Tuesday, March 25.

National Weather Service March 26, 2025 storm prediction graphic

On Wednesday, March 26, the National Weather Service issued a severe weather outlook for much of Western Washington, including King County. Heavy rainfall began that evening, and by 3:15 a.m. on Thursday, March 27, the Sum of the Snoqualmie River Forks data observed a flow of 12,070, triggering a Flood Phase 2 stage in the Snoqualmie River Basin. The Flood Warning Center was reopened at 4:45 a.m. and closed later March 27^th at 2:45 p.m.

The peak flow of 20,300 cfs for this multi-day flood event on the Snoqualmie River was observed on March 25 at 3:45 a.m. at the United States Geological Survey (USGS) gauge located on the Snoqualmie River near Carnation.

Chart of flow data for the Snoqualmie River Basin for the March 23-27 flood event

Tolt River

On March 23, the Tolt River reached Flood Phase 1 at 10:45 p.m. when 2,530 cfs was observed by the USGS gauge on the Tolt River near Carnation. Fluctuations in cfs were observed, with a peak of 3,300 cfs at 3:15 a.m. on March 24.

South Fork Skykomish River

Flood Phase 1 was observed multiple times on the South Fork Skykomish River between 12:00 a.m. on March 24 and 12:15 a.m. on March 28, as measured by the USGS gauge located on the South Fork Skykomish River near Skykomish. The peak flow was reached at 7:15 a.m. on March 27.

Green River

The Green River entered Flood Phase 1 on March 24 at 5:15 p.m. when 5,010 cfs was observed. A peak flow of 5,850 cfs was observed at 1:30 a.m. on March 26.

Cedar River

The Cedar River reached Flood Phase 1 on March 24 at 9:30 p.m. when 1,810 cfs was measured. The peak flow of 1,960 cfs was observed at 7:45 p.m. on March 27.

An interesting factoid: The last time the Flood Warning Center opened was on February 23, 2025.

Response Overview

This section lists some of the actions taken by the King County Flood Control District and its governmental partners. It is not intended to be an all-inclusive list of governmental actions taken during this flood event.

March 24: King County opened the Flood Warning Center at 12:45 a.m. to monitor flooding along the Snoqualmie River.
March 25: The King County Flood Warning Center closed at 7:45 a.m. after river conditions dropped below the Flood Phase 2 stage level.
March 27: King County opened the Flood Warning Center at 4:45 a.m. to monitor flooding along the Snoqualmie River.
March 27: The King County Flood Warning Center closed at 2:45 p.m. after river conditions dropped below the Flood Phase 2 stage level.

Communications Summary

This section lists some of the communications provided by the King County Flood Control District and its governmental partners. It is not intended to be an all-inclusive list of governmental communications provided during this flood event.

March 23 at 7:38 p.m.: Flood Warning System email sent from King County about the Snoqualmie River Basin indicating phase direction is moving upward, and Phase 1 flow is 6149 cfs based on the King County Sum of Snoqualmie River Forks.
March 23 at 11:38 p.m.: Flood Warning System email sent from King County about the Snoqualmie River Basin indicating phase direction is moving upward, and Phase 2 flow is 12,150 cfs based on the King County Sum of Snoqualmie River Forks.
March 23 at 11:38 p.m.: Flood Warning System email sent from King County about the Tolt River indicating phase direction is moving upward, and Phase 1 flow is 2,690 cfs was observed, based on the USGS gauge on the Tolt River near Carnation.
March 24 at 12:18 a.m.: Flood Warning System email sent from King County about the South Fork Skykomish River indicating phase direction is moving upward, and Phase 1 flow is 6030 cfs was observed, based on the USGS gauge on the South Fork Skykomish River near Skykomish.
March 24 at 12:52 a.m.: Flood Alert System phone call and email sent by King County indicating the Snoqualmie River has reached Flood Phase 2, and minor flooding is expected in low lying areas.
March 24 at 1:05 a.m.: King County provided an email update to the King County Flood Control District indicating the Flood Warning Center was activated at 12:45 a.m.
March 24 at 1:33 a.m.: King County provided an email update to area media outlets.
March 24 at 10:28 a.m.: Michelle Clark, Executive Director of the King County Flood Control District, provided an email update to the Board of Supervisors and an extended group of staff members. The Chair and Vice Chair were also contacted by text.
March 24 at 11:24 a.m.: King County Flood Control District posted a flood update on Facebook. Post was shared by SnoValley Chamber of Commerce, North Bend Downtown Foundation, North Bend Mayor Mary Miller, City of Carnation, and King County Flood Control District Vice Chair Sarah Perry.
March 24 at 11:27 a.m.: King County Flood Control District posted a flood update on X. Post was shared by City of Carnation.
March 24 at 11:28 a.m.: King County Flood Control District posted a flood update on Bluesky. Post was shared and received a comment.
March 24 at 5:59 p.m.: Flood Warning System email sent from King County about the Green River indicating phase direction is moving upward, and Phase 1 flow is 5,160 cfs was observed, based on the USGS gauge on the Green River near Auburn.
March 24 at 9:59 p.m.: Flood Warning System email sent from King County about the Cedar River indicating phase direction is moving upward, and Phase 1 flow is 1,810 cfs was observed, based on the USGS gauge on the Cedar River near Landsburg.
March 25 at 7:46 a.m.: King County provided an email update to the King County Flood Control District indicating the Flood Warning Center was closed at 7:45 a.m.
March 25 at 8:20 a.m.: Michelle Clark, Executive Director of the King County Flood Control District, provided an email update to the Board of Supervisors and an extended group of staff members. The Chair and Vice Chair were also contacted by text.
March 25 at 9:00 a.m.: King County provided an email update to area media outlets.
March 25 at 1:57 p.m.: King County Flood Control District reposted a flood update from the NWS on X.
March 25 at 2:40 p.m.: King County Flood Control District reposted a flood update from the NWS on X.
March 25 at 4:41 p.m.: King County reposted a flood update from the NWS on X.
March 25 at 7:21 p.m.: King County shared a flood update on Facebook from the NWS.
March 26 at 9:39 a.m.: King County Flood Control District posted a flood update on Facebook.
March 26 at 9:40 a.m.: King County Flood Control District shared a flood update on Facebook from the NWS.
March 26 at 9:43 a.m.: King County Flood Control District posted a flood update on X.
March 26 at 9:47 a.m.: King County Flood Control District posted a flood update on Bluesky.
March 26 at 11:49 a.m.: King County reposted a flood update from the NWS on X.
March 26 at 12:12 p.m.: King County shared a flood update on Facebook from the NWS.
March 26 at 12:52 p.m.: King County reposted a flood update from the NWS on X.
March 26 at 2:16 p.m.: King County reposted a flood update from the NWS on X.
March 26 at 3:12 p.m.: King County reposted a flood update from the NWS on X.
March 26 at 3:23 p.m.: King County reposted a flood update from the NWS on X.
March 26 at 3:28 p.m.: King County shared a flood update on Facebook from the NWS.
March 26 at 5:20 p.m.: Michelle Clark, Executive Director of the King County Flood Control District, provided an email update to the Board of Supervisors and an extended group of staff members. The Chair and Vice Chair were also contacted by text.
March 26 at 8:51 p.m.: King County reposted a flood update from the NWS on X.
March 27 at 3:15 a.m.: Flood Warning System email sent from King County about the Snoqualmie River Basin indicating phase direction is moving upward, and Phase 2 flow is 12,070 cfs based on the King County Sum of Snoqualmie River Forks.
March 27 at 4:42 a.m.: Flood Alert System phone call and email sent by King County indicating the Snoqualmie River has reached Flood Phase 2, and minor flooding is expected in low lying areas.
March 27 at 5:45 a.m.: King County provided an email update to area media outlets.
March 27 at 5:49 a.m.: King County provided an email update to the King County Flood Control District indicating the Flood Warning Center was activated at 4:45 a.m.
March 27 at 8:22 a.m.: Michelle Clark, Executive Director of the King County Flood Control District, provided an email update to the Board of Supervisors and an extended group of staff members. The Chair and Vice Chair were also contacted by text.
March 27 at 8:30 a.m.: King County provided an email update to the King County Flood Control District
March 27 at 2:56 p.m.: King County provided an email update to the King County Flood Control District indicating the Flood Warning Center was closed at 2:45 p.m.
March 27 at 3:00 p.m.: King County provided an email update to area media outlets.
March 27 at 3:08 p.m.: Michelle Clark, Executive Director of the King County Flood Control District, provided an email update to the Board of Supervisors and an extended group of staff members. The Chair and Vice Chair were also contacted by text.

Infrastructure and Critical Facilities

This section assesses the impact of flooding on critical infrastructure such as roads, bridges, utilities, and public facilities, and it highlights past investments which may have mitigated the impact of this flood event. It is not intended to be an all-inclusive list of flooding impacts, nor does it highlight all past government investment in area flood mitigation infrastructure.

The following roads were at risk for closure during this flood event:

Neal Road Southeast
Reinig Road
West Snoqualmie River Road Northeast (Walker Road)
Snoqualmie Meadowbrook Road
Mill Pond Road

The following images are associated with areas where river facilities exist. You can learn more about locations of river facilities, floodplains, and other important flood related information by using King County’s iMap.

A river facility refers to any man-made or engineered structure that interacts with a river system, with the purpose of influencing or controlling water flow, particularly to reduce flood risks. These include levees and revetments. A levee is a natural or artificial river embankment that prevents flooding, and a revetment is a passive structure that protects against erosion caused by river currents and high flows.

Stossel Bridge Right Bank Revetment on the right river bank of the Snoqualmie River.

A project is expected to go into construction at this location in 2025.

Stossell Right Bank Revetment on the Snoqualmie River

Sinnema Quaale Upper Revetment on the right river bank of the Snoqualmie River.

A project was completed at this location in 2016.

Sinnema Quaale Upper Revetment on the Snoqualmie River

Wallace Revetment on the left river bank of the Snoqualmie River.

Wallace Revetment on the Snoqualmie River

Roney Revetment on the left river bank of the Snoqualmie River.

Dutchman Road Revetment on the left river bank of the Snoqualmie River.

A project is being designed at this location.

Dutchman Revetment on the Snoqualmie River

Lessons Learned

This section lists some of the lessons learned by the King County Flood Control District and its governmental partners. It is not intended to be an all-inclusive list of governmental lessons learned during this flood event.

Flood forecasting and warning appeared to function as designed given there was no loss of life in King County during this flood event.
Existing flood risk reduction infrastructure appeared to function as designed given flooding impacts were minimal.
Media outreach and coverage appeared to function as intended to help keep the public properly informed and minimize public risks.
Flooding, while minor, underscores the policy position supporting the need for further investment in flood mitigation planning and projects.

Recognitions

The King County Flood Control District was created to provide funding and policy oversight for flood risk reduction capital projects and programs in King County. The Flood Control District brings a comprehensive approach to flood management and provides funding to improve the County’s aging and inadequate flood protection facilities, including flood control facilities, capital improvement projects, and floodplain management and restoration programs. Funding is also provided for a regional flood warning center and emergency response, flood facility maintenance, public education and outreach, mapping and technical studies, citizen inquiry, and public response.

During flood events, however, it is the Flood Control District’s governmental partners at King County and the other urban and rural cities throughout the county who are responsible for emergency services, transportation, public works, housing, and other government services critical for the protection of life and property.

The King County Flood Control District would like to recognize and show appreciation for the dedicated public services provided by those who work at National Weather Service, King County, and at cities throughout the county. These talented professionals work long hours during flood events, occasionally at risk to their own safety, to ensure the best possible outcomes for the citizens of King County.