CHEHALIS − NEAR GRAND MOUND (CGMW1)
   State:  Washington
   County:  Thurston
   Latitude:  46 46' 33" North
   Longitude:  123 2' 9" West
   Elevation:  124 ft

   Supporting NWS Forecast Office: WFO Seattle

   
Click for NWS Official River Forecasts for CGMW1
   


   Action Stage:  
138.5 ft
   Flood Stage:  
141 ft
   Moderate Flood Stage:  
142.5 ft
   Major Flood Stage:  
144 ft
Daily Historical Statistics for January 15, 2026
Mean Stage: 135.18 ft  Mean Flow: 6650 cfs
Max Stage: 142.52 ft  Max Flow: 26300 cfs (1975)
Min Stage:  130.59 ft   Min Flow: 970 cfs (1977)

Statistics based on water years: 1929-2025
* statistics estimated based on current rating

Record Stage: 
147.26 ft
Record Flow: 
79100 cfs
Date of Record: 
December 4, 2007

The 4-10 Day Trend Forecast is based on model guidance and uncertainty during this period is greater.

Hydrograph plot for CGMW1

Data Used In Plot   "label   USGS Observations