19-049 Boise River flows to decrease to 6,000 cfs on Friday

Published May 9, 2019


The U.S. Army Corps of Engineers will reduce flows through the City of Boise by 500 cubic feet per second (cfs) on Friday, May 10. Currently, Boise River flows through town are approximately 6,500 cfs, as measured at the Glenwood Bridge gauge. Flows will reach approximately 6,000 cfs by late-morning on Friday.

The decrease in flows from Lucky Peak Dam and Lake is in response to recent weather conditions and resulting inflows. The flow decrease is necessary to help balance reservoir-refill goals with the continued risk of flooding later during the spring, which can happen with rapidly melting snow and seasonal precipitation. As of May 8, the Boise River basin has received 109% of normal October-to-date precipitation, and the snowpack in the basin is 106% of normal according to the Natural Resources Conservation Service.

Additional adjustments in water releases from Lucky Peak Dam and Lake are likely during the coming days, depending on weather conditions and resulting inflows. Flows also could fluctuate depending on water diversions for irrigation use, as determined by Idaho Water District 63.

At 6,000 cfs, many sections of the Greenbelt path adjacent to the river will likely be submerged, and minor flooding may affect portions of Eagle Island. The Greenbelt serves as a flowage easement area, intentionally designed to provide space for higher flows occurring in the Boise River. A flow rate of 7,000 cfs, or about 10 feet in water depth, at the Glenwood Bridge gauge, is considered flood-stage level on the Boise River.

Officials advise the public to be aware of risks associated with flood season. The water is deep, cold and fast. Extreme caution should be used near the river banks.

Residents of flood-prone areas in and near the greater Boise area are encouraged to keep informed of changing river, stream, and weather conditions on the National Weather Service, Boise Office website at https://www.weather.gov/boi/. The site offers flow data, weather forecasts, and flood alerts. Follow flood-response instructions issued by your local emergency management agency https://adacounty.id.gov/emergencymanagement/, and tune-in to local radio and television news stations. Ada County residents can sign up for CodeRED emergency alerts at https://public.coderedweb.com/CNE/en-US/BF01DC4DD213, or download the CodeRED mobile app from your mobile device’s app store.

Currently, the Boise River reservoirs are at 81% of capacity. As of May 9, the Boise River system of reservoirs has about 184,500 acre-feet of available storage space. A full supply of irrigation water is anticipated this summer.

The Corps of Engineers and the Bureau of Reclamation operate three dams on the Boise River as a system to manage flood control and irrigation storage needs -- Lucky Peak Dam, Arrowrock Dam and Anderson Ranch Dam. Storage capacity provided by Reclamation’s Arrowrock and Anderson Ranch dams, and the Corps’ Lucky Peak Dam, combined with well-planned water releases, help manage Boise River flows through the City of Boise. For real-time Boise River flows at Reclamation facilities in the Pacific Northwest Region, visit https://www.usbr.gov/pn/hydromet/rtindex/boise.html.


Public Affairs Office

Release no. 19-049