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Great Plains Region
Billings, Mont.
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John Lawson
(307) 261-5671
Mark Andersen
(406) 247-7610

Released On: April 06, 2005

Fluctuation of Big Horn River Flow Downstream of Boysen Dam
The Bureau of Reclamation has evaluated a request from the Wyoming Game and Fish Department to provide a flushing flow in the Big Horn River downstream of Boysen Dam. Based on reservoir conditions and anticipated inflows to Boysen Reservoir, Reclamation has determined that a flushing flow can be provided in April without increasing the total amount of water to be released from Boysen Reservoir between April 1 and June 30, 2005, according to John H. Lawson, Area Manager of the Bureau of Reclamation, Wyoming Area Office in Mills, Wyoming.

The purpose of the flushing flow is to improve trout reproduction by flushing fine sediments from spawning gravels in the river. The flushing flow also improves insect production in the stream by opening up interstitial spaces between gravels and cobbles. The flushing flow is generally welcomed by anglers, because it provides easier wading conditions. Following the flushing flow, there is a reduction in floating algae, which is beneficial to fishermen as well as irrigation diversions. The flushing flow is being accomplished by retiming the release of water between April 1 and June 30, which results in no additional release of water from Boysen Reservoir than would be anticipated during this period.

On April 12 and April 13, 2005, flows in the river below Boysen Dam will fluctuate between approximately 1000 cubic feet per second (cfs) and 5000 cfs. On April 12 at 2:00 a.m., the release of water from Boysen Dam will be increased to 3000 cfs and at 7:15 a.m. increased to 5000 cfs for 10 hours before being gradually decreased to approximately 1000 cfs on April 13, 2005.

The public is urged to use extreme caution during this period of rapid fluctuation of flows below Boysen Dam.

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