Study flows from Harlan Lake releases
By Lori Potter, The Kearney Hub Staff
U.S. Army Corps of Engineers officials are watching rainfall totals and weather forecasts to judge whether releases from Harlan County Lake for a Republican River channel capacity study should be adjusted to avoid flooding.
"We're watching it very closely. We're aware of the pending precipitation," Jim Bowen, operations project manager for the Corps' Republican City office, said Monday afternoon.
Corps officials continue to be in contact with the National Weather Service and are monitoring weather radars on the Internet.
The study's goal is to understand the cumulative effects of time, drought, vegetation and clearing efforts on streamflow capacity. Over the past few years, Nebraskans have spent more than $850,000 to remove vegetation from Harlan County Dam downstream to the Kansas state line.
The information will help Corps officials make decisions about spring lake releases. The project is being coordinated with the federal Bureau of Reclamation, the state, natural resources districts and irrigation districts.
Bowen said lake releases of 300 cubic feet per second started Friday and increased to 700 cfs Saturday. The test maximum of 1,000 cfs was to have started Monday, but was delayed until this morning.
He said the Corps study crew from Kansas City set out temporary river gauges at a downstream target site on Monday that were checked first thing this morning.
"There was no appreciable rise in the river due to the rain or runoff," Bowen said, so the greater lake releases will be made and monitored.
"We will keep an eye on the precipitation coming in," he added.
Bowen explained that it takes two days after higher releases for flows to stabilize in the stretch of the river being studied by observing and recording conditions at highway river crossings. The study is scheduled to continue through Thursday.
Bowen said there were discussions Monday about potential rainfall effects on lake releases and the study's accuracy.
"People probably don't really understand what 700 to 1,000 cfs is in the river," he said, explaining that Harlan County lake releases for irrigation season are 10-750 cfs. That means Monday's flows of 700 cfs were on the high end of irrigation releases, and the 1,000 cfs level will exceed anything seen in the Republican River in recent years.
Bowen said there was a flood control release of 1,500 cfs in 1996, and the river channel handled that amount of water without significant flooding. Observing how the channel handles 1,000 cfs 14 years later will give researchers an idea of how drought and weed growth and weed removal have affected the stream's carrying capacity.
A Corps press release says river channel capacity was 6,000 cfs when the lake was constructed in the 1950s. The largest releases from the lake in 2009 were 900 cfs.
For more information, contact the Corps' Harlan County Lake project office at 308-799-2105 or the Kansas City Public Affairs office at 815-389-3486 or www.nwk.usace.army.mil.
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