Chehalis River near Grand Mound, WA
River level and flood forecast · Thurston County
The river is 12.1 ft below flood stage (141 ft).
Forecast to hold near 128.9 ft through Mon, Oct 19, 5 PM.
Flow: 256 cubic feet per second (USGS).
The last 7 days and the forecast
NWS forecast issued Mon, Oct 12, 8:27 AM. Forecasts change as rain falls and as upstream water arrives.
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An email when the National Weather Service forecasts Chehalis River near Grand Mound to flood, when it floods, and when it's over.
Flood stages
| Major flood stage | 144 ft |
| Moderate flood stage | 142.5 ft |
| Flood stage | 141 ft |
| Action stage | 138.5 ft |
| Record crest (December 4, 2007) | 147.26 ft |
What floods at each level
From the National Weather Service, highest first.
- 146 ftthe 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 ftthe 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 ftthe 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 ftthe 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 ftthe Chehalis River in Thurston County will locally spill out of its banks into nearby fields and over a few roads.
Highest crests on record
- 147.26 ft — December 4, 2007
- 145.21 ft — January 7, 2022
- 143.27 ft — December 11, 2025
- 142.88 ft — January 14, 2021
- 142.68 ft — December 22, 2019
Recent crests: 143.27 ft (December 11, 2025) · 140.85 ft (January 28, 2024) · 142.28 ft (December 7, 2023) · 142.59 ft (March 2, 2022) · 145.21 ft (January 7, 2022)
Up and down the river, and nearby
Not an official source. River levels, forecasts, flood stages and impacts are from the National Weather Service (CGMW1); flow from the U.S. Geological Survey. Readings are provisional. In a flood, follow your local officials and the NWS at weather.gov.