BOISE -- The Boise River is rising and is now higher than it has been all year.
To help deal with all the water that is filling the reservoir from the recent rain and snow pack melt, starting today, the U.S. Army Corps of Engineers and the Bureau of Reclamation is increasing flows from Lucky Peak Dam into the Boise River, to help reduce the risk of severe flooding during the coming weeks.
According to the U.S. Geological Survey, the Boise River is at about 10.5 feet, flood stage is 10 feet.
Flows from Lucky Peak will increased by 300 cubic feet per second (cfs) on Tuesday and another 200 cfs on Wednesday. This is expected to cause the river to rise about 3 to 4 inches at the Glenwood Bridge.
Record rainfall last week and more storms later this week are spurring water managers' decision to increase the flows from Lucky Peak. They also want to maintain storage capacity and protect downstream areas from flooding.
Rapid snow melt at higher elevations is causing concern about flood risks, and putting more runoff into streams and rivers.
“This year’s heavy rainfall on top of rapidly melting snow pack differs from what the Boise Valley experienced last year,” noted Lt. Col. David A. Caldwell, the Corps’ Walla Walla District commander. “In 2011, moderate rainfall and low overnight temperatures allowed snow to melt slowly. Conditions are not as favorable this year, making it critical to keep flows high right now in order to mitigate the need for much higher flows at a later date.”
Current water storage in the Boise River reservoirs -- Lucky Peak, Arrowrock and Anderson Ranch dams -- is about 90 percent of capacity. Water managers say water volume from melting snow pack and forecasted storms over the next two to three weeks will make it necessary to increase those releases.
Flood stage at the Glenwood Bridge is around 7,000 cfs. At 8,000 cfs, larger sections of the Boise Greenbelt along the Boise River will be submerged. Erosion along the river banks will become a significant problem. Minor flooding may occur on section of Eagle Island and other low lying areas near the river. There will likely be more standing water in those areas over the next few days.
Some homes and businesses may experience water in their basements due to subterranean water level increases.
Officials are warning people to be aware of the flow increases and take precautions along the Greenbelt and near the Boise River. The water will be deeper and moving faster. Also, the water temperatures are very cold right now. It is best to stay out of the river.
The last time flows at the Glenwood Bridge reached 8,000 cfs was in 1998.
Water managers say that additional increases may be necessary due to rainfall and snow melt. The good news is that there will likely be a fully supply of irrigation water for farmers and ranchers this season.