Saylorville Lake Inflows Will Overtop Spillway - Update

Published June 30, 2010

Des Moines, Iowa -- (June 30, 2010) Inflows into the Saylorville Lake from its 5,823 square-mile watershed on the Des Moines River continue to cause pool levels to rise.  In response to rainfall occurring over the Des Moines River watershed and subsequent increased inflows into Saylorville Lake, the U.S. Army Corps of Engineers continues to release its maximum outflow from its conduit.

Saylorville Lake level is currently at 886.79 feet and rising using approximately 91.3 percent of its available flood storage.  Inflow into the reservoir is expected to raise the pool level to 889 feet (five feet above the concrete spillway crest of 884 feet) by tomorrow morning, Thursday, July 1.  The Corps has raised the spillway's inflatable dam (pneumatic crest gates) to provide an additional six feet of spillway elevation to 890 feet.

Forecast models indicate the lake level will continue to rise surpassing 889 feet and overtop the pneumatic crest gates; therefore, the crest gates will begin to be lowered at approximately 6 a.m. on July 1.  Combined outflows from the lake's conduit and spillway could approach 39,000 cfs after lowering the crest gates.  Today's forecast indicates water will be below 884 feet (below the concrete spillway) by Thursday, July 8.  The maximum outflow from the lake during the 2008 flood was 47,000 cfs on June 12, 2008.

Saylorville Lake's inflow on Tuesday morning, June 30, is approximately 50,500 cubic feet per second (cfs) with an average outflow of 21,000 cfs.  Saylorville is currently storing 591,530 acre feet of water (192.75 billion gallons).  The record high stage at Saylorville Lake was 892.03 feet on July 11, 1993.

Increased conduit releases are necessary to gain additional flood storage as quickly as possible.  Lake discharge, combined with flows from tributaries below the lake will result in downstream flooding.  Residents in flood-prone areas along the Des Moines River watershed should be alert to rising water levels and begin preparation for higher water.

Updated information about Saylorville Reservoir is available on the web by visiting the Corps’ website at  This web site includes links to the U.S. Army Corps of Engineers and National Weather Service websites that track Saylorville Reservoir elevations, Des Moines River flow and projected rainfall amounts.

Release no. 10-06-30