LINCOLN – On Nov. 14, a single live adult zebra mussel was discovered attached to a boat dock at the Midway boat ramp on the South Dakota side of Lewis and Clark Lake near Yankton, S.D.
South Dakota Game, Fish and Parks (SDGFP) staff inspected 11 additional boat docks and shorelines and found no additional zebra mussels in or near the lake. Several boats stored at a marina also were inspected and no mussels were found, though many boats already were power-washed for winter storage. SDGFP and the Nebraska Game and Parks Commission have sampled the lake yearly for zebra mussel veligers (larva) and all samples have been negative.
It is likely the discovered mussel came from a contaminated boat that launched near the site the zebra mussel was found. As a result of this discovery, Lewis and Clark Lake is now classified as a “suspect waterbody” for zebra mussels and will remain that way for at least three years if no additional mussels are found.
In September, an invasive quagga mussel was found in Angostura Reservoir in southwest South Dakota. Nebraska has only one documented invasive mussel infestation, in the Offutt Air Force Base Lake in Bellevue. The lake has been closed to motor boats since 2006.
These newly-discovered quagga and zebra mussels in South Dakota increase the need for formal boat inspection programs in South Dakota and Nebraska to reduce the spread of invasive mussels to other water bodies. Both states have regulations intended to prevent the movement of invasive mussels into additional waterbodies, but both have limited funding to deal with invasive species and lack a formal program to inspect watercrafts at all high-risk reservoirs.
Staff from both states will discuss this issue and develop a future action plan for Lewis and Clark Lake.
For more information, visit the Nebraska Invasive Species Program at neinvasives.com.