Boise River flows to near "bankfull" today

Posted at 7:45 AM, Apr 23, 2019
and last updated 2019-04-24 04:59:29-04

BOISE — The U.S. Army Corps of Engineers and the Bureau of Reclamation will increase flows through the City of Boise by 500 cubic feet per second (cfs) Wednesday.

Currently, Boise River flows through town are approximately 5,800 cfs, as measured at the Glenwood Bridge gauge. Flows will reach approximately 6,300 cfs by mid-morning Wednesday.

The increase in flows from Lucky Peak Dam and Lake is in response to above-average precipitation the Boise River System so far this month. As of Monday, April 22, the Boise River basin has received 197% of normal month-to-date precipitation -- and the snowpack in the basin is 126% of normal according to the Natural Resources Conservation Service. These increases are necessary to help reduce the risk of flooding later in the spring, which can happen with rapidly melting snow and seasonal precipitation, According to the U.S. Army Corps of Engineers.

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.

A flow rate of 6,500 cfs, or about 9.6 feet in water depth, at the Glenwood Bridge gauge is considered bankfull. As the river nears that level, large sections of the Greenbelt path next to the river will likely be submerged. 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, according to officials.

They 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. 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.

Residents of flood-prone areas in and near the Boise area are encouraged to stay informed of changing river, stream and weather conditions on the National Weather Service website.

Currently, the Boise River reservoirs are at 77% of capacity. A full supply of irrigation water is anticipated this summer.