CENTERVILLE, Iowa --
At present, Rathbun pool elevation is about half a foot above multipurpose 904.0 feet. Current conditions at Rathbun Lake appear to be unfavorable for the U.S. Army of Corps of Engineers to conduct a fall water release in either late September or early October 2021.
The pool does not have sufficient water in storage to sustain the release, as the pool needs to be at elevation 905.6 feet or higher to have the volume of water necessary to support the fall release, intended to benefit state and privately managed conservation and recreational areas along the Chariton River.
Following a rain even in mid-July that provided inflows and sustained baseflows below the dam, releases from Rathbun were set to establish a lake elevation of 905.0 feet, affording a little buffer against effects of evaporation but still allowing the pool to rise with the next rain event. However, rains and inflow into Rathbun Lake through the month of August proved to be unseasonably low.
During the month of August, the lake received only 28% of average inflow volume, a significant factor in determining if a fall release can be performed. As a result, the release has been set to low flow, about 11 cubic feet per second since 11 August 2021.
The difference between having sufficient storage to sustain the fall release can be the occurrence of one modest and appropriately timed rainfall event. One rain event producing .5 inch of runoff across the watershed may be sufficient to raise the reservoir from elevation 904.0 feet to 905.6 feet. Runoff is the amount of rain that does not get captured by soil or impoundments during a rain event. The National Weather Service 7-day forecast predicts little to no rain for Rathbun Lake area.
If the pool elevation has not risen to 905.6 ft by early October, no fall water release will be conducted this season.
Questions and comments regarding this water release can be directed to the Rathbun Lake Project Operation Office Manager at 641-647-2464 or the Kansas City District Water Management Office at 816-389-3545.
Release no. 21-055