COLUMBIA − BLO ROCK ISLAND DAM (RISW1)
   State:  Washington
   County:  Douglas
   Latitude:  47 19' 57" North
   Longitude:  120 4' 48" West
   Elevation:  609 ft

   Supporting NWS Forecast Office: WFO Spokane
   Click for NWS Official River Forecasts for RISW1
   
Daily Historical Statistics for June 11, 2026
Mean Flow: 199000 cfs
Max Flow: 532000 cfs (1961)
Min Flow: 66700 cfs (1977)

Statistics based on water years: 1961-2025
* statistics estimated based on current rating

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

Hydrograph plot for RISW1

Data Used In Plot   "label   Chelan County Public Utility Observations   Rocky Reach Dam   USACE Map   


Hydrograph plot for RISW1

Data Used In Plot   "label   Chelan County Public Utility Observations   Rocky Reach Dam   USACE Map   


Hydrograph plot for RISW1

Data Used In Plot   "label   Chelan County Public Utility Observations   Rocky Reach Dam   USACE Map   


Hydrograph plot for RISW1

Data Used In Plot   "label   ---