One community in northeastern South Dakota is sharing how it came together to combat an invasive species that threatened its neighboring body of water.
Zebra mussels are not welcome at Enemy Swim Lake in Day County.
When they showed up in Pickerel Lake last summer, Ron Schreiber, a resident around Enemy Swim Lake, fielded a call asking him to join the Enemy Swim Preservation Association. He initially declined because he thought zebra mussels spread from lake to lake by birds carrying them. But after speaking with Meg Duhr and Megan Weber of the University of Minnesota's Aquatic Invasive Species Research Center, he learned the spread is more likely caused by boat traffic. If zebra mussels were carried from lake to lake by birds, most lakes in the area would already be infested, Schreiber reasoned.
While zebra mussels have been in Minnesota for 32 years, only 3% of the state's lakes are inhabited by them due to prevention measures. So far, Enemy Swim Lake stayed off of South Dakota's list of lakes troubled by the pests.
Why are zebra mussels so bad?
Zebra mussels have the potential to harm aquatic ecosystems and affect municipal and agricultural water systems. They are "filter feeders that consume plankton and algae in the water. Each individual is capable of filtering over one liter of water per day," according to information from the South Dakota Department of Game, Fish and Parks.
They also attach to the insides of engine cooling systems in boats and water intake structures and restrict the movement of water, according to GFP.
Zebra mussels have extremely sharp shells, which can be painful when people step on them. That's been a problem at Lake Kampeska in Watertown, where the creatures were confirmed last summer.
Dave Charron, who has a cabin on Enemy Swim Lake, said there have been similar problems at Pickerel Lake.
Pickerel and Kampeska are two of the most popular lakes in the region.
In South Dakota, zebra mussels have also been confirmed in Lake Yankton, Lewis and Clark Lake, McCook Lake, the Missouri River below the Gavin's Point Dam, Lake Cochrane, Lake Francis Case and, as of Monday, Lake Mitchell, according to the GFP.
According to the U.S. Geological Survey, the mussels a species native to Eurasia. It's believed that they showed up in the Great Lakes in the 1980s from European ships emptying ballast water. They've been spreading in the U.S. since.
The mussels can even take over hydroelectric and nuclear power plants, public water supply plants and industrial facilities, according to the USGS. Companies may have to spend millions of dollars to have them removed.
Schreiber said that when zebra mussels filter the water, which makes the water appear clearer. However, this will ultimately do more harm to the lake, as the mussels will get rid of green algae, disrupting the ecosystem for organisms that feed on it and trickling down the entire food chain, he said.
Because there are boats going in and out of so many different lakes that have zebra mussels, the Enemy Swim Preservation Association advocated to the GFP to put money toward ensuring that no boats with zebra mussels would enter Enemy Swim. But GFP didn't have the money, Schreiber said.
The Enemy Swim Preservation Association then asked if people could be employed through GFP if the association found both the works and the funds. GFP agreed to that, and that led to the lake's prevention effort.
At the beginning of the summer, Schreiber said, there were two college students who took jobs as watercraft inspectors. That number eventually increased to three. However, the days are hot and long, and Schreiber said even more workers would be ideal.
In total, preservation association raised about $49,000 through crowd funding, and has spent about $25,000, said Schreiber. The group reimbursed the state for the wages, as well as mileage for employees traveling to and from the lake.
In neighboring states like Montana and Wyoming, boat inspections are standard, he said. But in South Dakota, Enemy Swim is the first lake association to do such inspections, said GFP conservation officer Nick Cochrane. He added that the state has been preparing for zebra mussels for years by doing highway boat inspections.
The Enemy Swim Lake efforts work. Between May 21 and Aug. 24, the employees inspected 1,519 boats going into lake, and zebra mussels have not been found.
The big test will come when veliger test is performed, which tests for the presence of larvae using an extracted water sample. Schreiber said the Enemy Swim Preservation Association will reevaluate its plan for next summer, depending on if the test comes back positive or negative. Once zebra mussels are in a lake, little can be done to take them out.
Residents near other South Dakota lakes are interested in how zebra mussels were prevented in Enemy Swim. Cochrane said the Richmond Lake Association near Aberdeen is currently in communication with GFP.
Schreiber said preservation association's next goal is to schedule a meeting with GFP in Webster at the end of the month. Representatives from other local lakes will be invited. They will recap this past summer and discuss a plan for next summer. The group also hopes to fly out Duhr from Minnesota to help discuss the importance of preventing zebra mussels.
While Schreiber that Enemy Swim Preservation Association hopes for more funding for the state. He said it all comes down to politics and whether the state wants to put forward the funding.
GFP offers the following tips to help prevent the spread of zebra mussels:
- Clean watercraft and trailers of all aquatic plants and mud.
- Drain all water by removing all drains, plugs, bailers, or valves that retain water. Be sure to completely drain your lower unit of any water by lowering completely.
- Dispose of unwanted bait in trash or fish cleaning stations when leaving the water.
- Completely draining a boat is the first step in making sure invasive species are not transferred to other waters.