Major Flood
144 ft
Current Water Level
Gage Height
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Streamflow
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Last Reading
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FLOOD STAGES
Know the flood categories.
Flood stages defined by the National Weather Service. Gage height data from USGS Water Resources.
Moderate Flood
142.5 ft
Minor Flood
141 ft
Action Stage
138.5 ft
What Floods at Each Level
146 ft
the Chehalis River in Thurston County will cause severe near record flooding, with deep and swift flood waters inundating the Independence Valley. Flooding will occur all along the river including headwaters, tributaries, and other streams within and near the Chehalis River Basin.
144.5 ft
the Chehalis River in Thurston County will cause major flooding, inundating roads and farm lands in Independence Valley. Deep and swift flood waters will cover SR-12 and James, Independence and Moon Roads. Flooding will occur all along the river including headwaters, tributaries, and other streams within and near the Chehalis River Basin.
142.5 ft
the Chehalis River in Thurston County will flood several roads in Independence Valley with swiftly moving water including SR-12 and James, Independence, Moon and Anderson Roads. Flood waters will cut off access to and from Chehalis Reservation and inundate nearby farm lands. Some residential structures may be threatened.
141 ft
the Chehalis River in Thurston County will flood several roads in Independence Valley including James Road, Independence Road, and Moon road. Flood waters will also cover nearby farm lands.
139.5 ft
the Chehalis River in Thurston County will locally spill out of its banks into nearby fields and over a few roads.
Impact statements from the National Weather Service, describing what typically happens at each water level.
7-Day Water Level Chart
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Historic Crests
| Date | Stage | Flow |
|---|---|---|
| Dec 4, 2007 | 147.26 ft | 79,100 cfs |
| Jan 7, 2022 | 145.21 ft | 51,269 cfs |
| Dec 11, 2025 | 143.27 ft | 32,114 cfs |
About This Gauge
USGS Site
NWS LID
CGMW1
River
Chehalis River
County
Thurston, WA
Coordinates
46.7759°N, 123.0357°W
Get Flood Alerts for Chehalis River
StormCast monitors this gauge and sends a push notification to your phone when the water level crosses into a new flood category — even at 3 AM.
Frequently Asked Questions
What is the current water level of Chehalis River near Grand Mound?
The Chehalis River near Grand Mound gauge is maintained by USGS (site 12027500) and reports water levels every 15 minutes. Visit this page to see the latest reading updated live, or download StormCast to get push alerts when levels rise.
What is flood stage for Chehalis River near Grand Mound?
The NWS-defined flood stage for Chehalis River near Grand Mound is 141 feet. Action stage begins at 138.5 feet. Moderate flooding starts at 142.5 feet, and major flooding at 144 feet.
How do I get alerts when Chehalis River rises?
Download StormCast free on Google Play, go to River Gauges, and add Chehalis River near Grand Mound to your watchlist. StormCast will send a push notification to your phone whenever the water level crosses into a new NWS flood category.
Where is the Chehalis River near Grand Mound gauge located?
The gauge is located in Thurston County, Washington at coordinates 46.7759°N, 123.0357°W. USGS site number: 12027500. Data is provided by the U.S. Geological Survey and the National Weather Service.
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Source & Notes
Data provided by: US Geological Survey, Observations courtesy of U.S. Geological Survey
- River forecasts for this location take into account past and future precipitation. The stages/flows that will occur may be different if future rainfall is different than forecast.