Boaters enjoying Lewis and Clark Lake should expect to have their boats inspected when coming off the water in upcoming weeks after several boats moored in the reservoir were discovered to have zebra mussels attached.
The South Dakota Game, Fish and Parks said mussels were of multiple sizes, indicating that zebra mussels are reproducing in Lewis and Clark Lake.
In November 2014, a single adult mussel was found by the South Dakota Game, Fish and Parks (GFP) staff on a dock removed from the lake.
That discovery, along with the discovery of larval quagga mussels at Angostura Reservoir in western South Dakota, prompted GFP officials to put new rules in place prompting boaters to remove all drain plugs from watercraft prior to leaving boat ramp areas. While officials believe that most boaters are complying with the law, the now confirmed presence of these invasive mussels makes compliance even more critical.
“Boaters will see an increase of GFP staff at all Lewis and Clark Lake boat ramps,” said GFP assistant director of the Division of Wildlife, Arden Petersen. “We want to make sure people are aware of the regulations and the importance of draining all water from their livewells, baitwells and hulls.”
Zebra mussels are a small, invasive mollusk (clam) that originated in Eastern Europe and first arrived in the U.S. in the mid-1980s. Although usually less than an inch in size as adults, they can rapidly spread under the right conditions. These mussels can clog irrigation lines and damage boat motors and docks and their sharp shells can wash up on shorelines in large numbers making recreation difficult.
“Lewis and Clark Lake is at the bottom of our Missouri River reservoir system and this could potentially affect all waters below the Gavins Point Dam,” said GFP chief of aquatics, John Lott. “The most likely way for these mussels to be transferred up river is on boats or in water contained by boats.”
The larval stage of zebra mussels, called veligers, are nearly impossible to detect due to their small size, heightening the importance of the state’s new boat draining laws. 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.
“Right now South Dakota waters are at peak water temperatures for veligers to spread,” said Lott. “Boaters on Lewis and Clark Lake need to be extra diligent and completely drain their boats before leaving boat ramp areas.”
Completely draining a boat is the first step in making sure invasive species are not transferred to other waters. Boaters should clean their boats with 140 degree water and let them completely dry before launching their boats in other water bodies.