JOHNSTON, Iowa – The Corps of Engineers is implementing additional measures in an effort to keep water from flowing over Saylorville Lake's spillway. Recent rains and snowmelt due to higher-than-expected temperatures in the Des Moines River basin have increased inflows into the Lake resulting in the projected Lake elevation exceeding previous estimates.
On Monday, March 8, working with the City of Des Moines, the Corps implemented a deviation to operate the lake to control for a stage of 26 feet at the S.E. 6th Street gage in Des Moines, an increase of two feet above the authorized control stage of 24 feet. The deviation allowed higher outflows between March 8 and April 20 to keep the lake at its lowest possible level without causing additional flood damages downstream.
The Lake, currently forecast to exceed the top of the spillway's bladder dam, could cause outflows in excess of 40,000 cubic feet per second (cfs) if waters overtop the spillway. Flows at that level could threaten the Central Place and Birdland Park levees.
To address the revised Lake elevation estimates, the Corps, working with the City, approved a second deviation in an effort to prevent an overtopping event. The new deviation abandons the constraint at the S.E. 6th Street gage sooner than the current plan dictates, allowing as much as 21,000 cfs of water to be released from Saylorville Lake. This translates to river levels about 10 feet below the top of the Central Place and Birdland Park levees in downtown Des Moines.
By adjusting the Lake’s Regulation Plan and increasing releases to 21,000 cfs one week earlier than the S.E. 6th Street gage constraint allows, the Lake may be able to keep flood waters from overtopping the spillway's bladder dam. Operation of the lake at this level should stave off the projected peak inflows of more than 45,000 cfs.
The deviation will increase Lake Red Rock inflows temporarily but the eventual peak elevation will not be any different with this deviation. Lake Red Rock releases will not be increased above the regulated, non-damaging, maximum outflows.
The flood storage pool consists of approximately 567,400 acre feet of water (184.8 billion U.S. gallons).
# # #
EDITOR’S NOTE:
For more information contact:
Saylorville Lake Deviation: Tom Heinold, Flood Area Engineer, Des Moines area, (309) 794-5203, Thomas.D.Heinold@usace.army.mil
Saylorville Lake Operations: Jeff Rose, Operations Manager, (515) 276-4656 x6504, Jeffrey.W.Rose@usace.army.mil
Lake Red Rock Operations: John Holt, Assistant Operations Manager, (641) 828-7522 x6404, John.F.Holt@usace.army.mil
General Corps of Engineers Information: Ron Fournier, Corporate Communications, (309) 794-5274, Ronald.F.Fournier@usace.army.mil