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Swift Dam is full, water being released through spillway

Posted at 4:04 PM, May 27, 2019
and last updated 2019-05-27 20:18:41-04

Several areas in north-central Montana are grappling with excess water, including two dams along the Rocky Mountain Front.

Swift Dam, which is west of Dupuyer, is full and water is running over the spillway while Gibson Dam, which is 70 miles west of Great Falls, is almost full.

According to Vern Stokes, manager of the Pondera County Canal and Reservoir Company, 2,300 cfs (cubic feet per second) of water is being released through Swift’s gates while 250 cfs is going over the spillway.

“We should start seeing a drop later this afternoon or tomorrow,” Stokes added. “I’m monitoring the situation up there all the time.”

Swift Reservoir holds around 30,000 acre feet of water. According to the National Park Service, an acre foot is enough to cover one acre a foot deep or 325,851 gallons. A gallon of water weighs 8.33 pounds and an acre foot of water weighs 1,357 tons.

Lake Frances in Valier, which receives water from Swift, is full so the water is being directed down Birch Creek and into Tiber Reservoir in southern Liberty County.

The Cascade County Sheriff’s Office reported Monday Gibson Dam is almost full due to the heavy rain and melting snow.

Officials are preparing to open Gibson Dam to release the overburden of water. When the dam is opened, the Sun River will experience flooding in low-lying areas, according to the CCSO.

Gibson Dam is able to store 99,000 acre feet of water in its reservoir. As of May 26, Gibson Reservoir was 93.9 percent full and pool elevation was recorded at 4719.4 feet. The reservoir flood control pool was zero percent filled.

Gibson Dam is on the Sun River and Sun River is a tributary of the Missouri River.

For more information or a history of Gibson Dam and Reservoir, please visit the National Park Service’s website.

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