Missouri River Water Management News

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Zebra Mussels discovered at Lewis and Clark Lake

Published Sept. 17, 2015
A handful of Zebra Mussels.

A handful of Zebra Mussels.

OMAHA, NE — South Dakota declared Lewis and Clark Lake "Infested" for zebra mussels on August, 20, 2015. Previously the lake had been considered "Suspect" after the discovery of a single adult zebra mussel in November 2014. The change in status resulted from confirmed presence of a breeding population within the reservoir.
The latest information confirms populations of zebra mussels throughout the lower third of the reservoir and within the river segment just below Gavins Point Dam. Upstream inspections included Lake Francis Case (Fort Randall Project) and found no evidence of zebra mussels. The infestation appears to be limited to the lower third of the Lewis and Clark reservoir and to an unknown extent downstream of Gavins Point Dam.
The Omaha District Corps of Engineers is working with other federal, state, and local agencies to develop a coordinated response to the discovery. Agencies are currently investigating the extent of the infestation below Gavins Point Dam and increasing boat inspections around Lewis and Clark Lake and the Missouri River. South Dakota and Nebraska have implemented regulations requiring that boats must be drained of all water prior to leaving a launch area and have drain plugs removed while in transit.
Zebra mussels are a small, invasive mollusk (clam) usually less than an inch in size as adults. The larval stage of zebra mussels, called veligers, are nearly impossible to detect due to their small size. Veligers can be easily transported to new waters in even a small amount of water remaining anywhere in a boat or watercraft after a fishing or boating trip. They can rapidly spread under the right conditions and have the potential to clog water intake structures, attach themselves to docks, boat motors and anything else that rests in the water for periods of time.
The Corps of Engineers routinely inspects water control and hydropower infrastructure for indications of zebra mussel fouling. In light of the confirmed infestation in the reservoir, the Corps will be performing additional inspections during routine maintenance sessions.

For more information about zebra mussels and how you can assist in the effort to control the population, please visit:

• http://www.100thmeridian.org/ - For boaters, anglers, and aquatic recreational users
• http://snr.unl.edu/invasives/ - Nebraska Invasive Species Project
• http://sdleastwanted.com/ - South Dakota Game Fish and Parks

Also, visit the U.S. Army Corps of Engineers, Omaha District, on Facebook to stay updated on the progress of efforts to control the zebra mussels: www.facebook.com/OmahaUSACE

Jonas Grundman

Release no. 2015-09-17-001