Columbia Basin Flood Risk & Forecast Information

2020 CRSO EIS.

Libby Dam and Hungry Horse Dam VARQ operations are included in the CRSO EIS available from www.nwd.usace.army.mil/CRSO/.

Storage Reservation Diagrams (SRD) define the flood control space required in each reservoir to provide flood protection for the Columbia River. Storage space required is a function of time of year and the seasonal runoff volume. The diagrams are designed to provide an orderly evacuation of each reservoir prior to the reservoir refill period with consideration to project operating limits and the regulation of the Columbia River reservoir system.   

Current SRDs

• Libby - System VARQ Flood Space Diagram, October 2020
• Libby - System VARQ Flood Space Table, October 2020
• Hungry Horse - July 1998 VARQ SRD
• Grand Coulee – System Flood Space Diagram, August 2022
• Grand Coulee – System Flood Space Table, August 2022
• Dworshak - System flood control, February 1987 SRD
• Dworshak - Local flood control, November 1992 SRD
• Brownlee - November 1998

Previous SRDs

• Mica - 2.08 Maf Primary storage space, September 1972 SRD
• Arrow - 5.1 Maf Primary storage space, September 1972 SRD
• Mica - 4.08 Maf Primary storage space, January 1995 SRD
• Mica - On-call storage space, September 1972 SRD
• Arrow - 3.6 Maf Primary storage space, January 1995 SRD
• Duncan - November 2009 SRD
• Duncan - September 1972 SRD
• Libby - System flood control, June 1991 SRD
• Libby - System flood control, September 1972 SRD: available on request
• Libby - Local flood control, September 1972 SRD
• Libby - System VARQ Flood Control, December 2003
• Libby - System VARQ Flood Control, December 2012
• Hungry Horse - December 1995 SRD
• Grand Coulee - March 1997 SRD
• Grand Coulee - 2015 SRD
• Grand Coulee - System Flood Space Diagram, October 2020
• Grand Coulee - System Flood Space Table, October 2020

The principles of Columbia River flood risk management regulation have been documented in Columbia River Treaty Flood Control Operating Plans (FCOPs). Previous FCOPs are below:

• Treaty Flood Control Operating Plan, May 2003: available on request
• Treaty Flood Control Operating Plan, October 1999: available on request
• Treaty Flood Control Operating Plan, October 1972: available on request