SIOUX FALLS, S.D. (KELO) — About a year ago, Dan Loveland said he was learning to live with zebra mussels on Pickerel Lake in eastern South Dakota.

The lake had an explosive growth of the invasive species after it was discovered about 13 months prior, Loveland said.

This month, Loveland learned a little more about how long he and other cabin owners on the lake may need to live with zebra mussels.

Loveland said he and others resurrected the South Dakota Lakes and Streams Association this year. The association is helping to educate the public and property owners about how to prevent the spread of invasive species such as zebra mussels as well as how to respond once they are discovered.

Last week, the association organized an update from an invasive species researcher from the University of Minnesota.

Loveland said it was a mixture of bad and news and hopeful news.

“The bad news is zebra mussels are in South Dakota and they are spreading,” Loveland said.

The spread of zebra mussels and other invasive species, including aquatic plants, is dangerous for a lake’s ecosystem.

Zebra mussels in Pickerel Lake are a particular threat to walleyes. The researcher explained that zebra mussels and walleye minnows eat the same kind of plants. Minnows may not have enough food supply and won’t grow as fast. That makes them more vulnerable to predators in their first year of life.

That’s not great news for a lake that draws fishermen from across the state as well as neighboring states.

But, the researcher also had some other news.

“Progress is being made to control and even eradicate zebra mussels and other invasive species,” Loveland said.

“Her message to us was do whatever we can to slow down the spread,” Loveland said.

Property owners on Enemy Swim Lake have been doing what they can since 2021.

Cabin owner Ron Schreiber said Pickerel Lake is about a mile from Enemy Swim. When zebra mussels were found on Pickerel, “(cabin) owners on Enemy Swim became concerned about the spread to our lake,” Schreiber said.

Any watercraft including boats, kayaks and inflatables can carry zebra mussels, their larvae or eggs. If water is not cleared from the interior, engine and exterior areas of a watercraft there is increased risk of carrying an invasive species from an infested lake to another lake.

Photo courtesy: Dan Loveland.

The Enemy Swim Preservation Association organized fundraisers to work with the South Dakota Game Fish and Parks department on a watercraft inspection program that started in 2021.

The Enemy Swim group has raised about $70,000 to pay for costs associated with GFP summer interns inspecting watercraft. Volunteers from the lake group help on weekends.

The partnership between the GFP and Enemy Swim has been a good one, Schreiber said.

“Throughout the two years, the level of communication has been fantastic,” he said.

About 1,800 watercraft were inspected last year. The count will not be as high this year because there have been fewer boats at the lake, Schreiber said.

Watercraft are inspected seven days a week from 7 a.m. to 7 p.m. The GFP interns and volunteers check the bait wells, motors, and other interior of the boat as well as the exterior. If a boat hasn’t pulled its plug to drain excess water or has water in a bait well, before it enters Enemy Swim, that boat is cleaned with a high-pressure washer with water that heats to 120F for interior cleaning and 140F for exterior cleaning, Schreiber said.

“Because we not 24/7, boats can come in before the site is open or come in after it’s closed,” Schreiber said. “So boats can (potentially) still bring in zebra mussels.”

The GFP said on July 25 that two zebra mussels were found on two different days in July. Enemy Swim was considered infested with zebra mussels, the GFP said on July 25.

But Schreiber said property owners aren’t convinced yet of the infestation. A zebra mussel found on one rock and another found about two weeks later may not be enough to indicate an infestation, Schreiber said.

The inspection of watercraft continued with the GFP and volunteers until mid-August. Volunteers will take over until mid-September, he said.

The lake’s preservation association has also continued to examine the lake for zebra mussels. The lake’s preservation association tests the water in various location.

“The samples have come back negative with no evidence of zebra mussels,” Schreiber said.

A scuba dive team from the Big Stone Lake area was hired to inspect the lake for zebra mussels. The divers searched the lake at depths from eight feet to 25 feet. The search included bringing up rocks from those sites.

“All the findings came back negative for zebra mussels,” Schreiber said.

Schreiber said until there is more convincing evidence of an infestation, inspections and testing will continue.

He too, cited the Minnesota researcher’s advice to do as much as possible to slow the spread of invasive species.

If Enemy Swim can last three or four years without an infestation, research may have developed a solution by then, Schreiber said.

“They’ve identified the genome of the zebra mussel,” Schreiber said. That could lead to a solution that applies only to the zebra mussel and won’t harm other species, he said.

Loveland said the joint GFP and volunteer project at Enemy Swim could be adopted by other lake associations if the GFP is willing.

The GFP could also use seasonal staff as boat inspectors in addition to other duties they do at state parks, Loveland said.

A fresh water hose to clean boats could also be added at lakes where the state has water for fish cleaning stations, Loveland said.

Loveland said representatives of the lakes and streams association met with GFP officials to discuss some ideas for protecting the state’s lakes.

The GFP has had inspection stations at several lakes this summer. The department repeatedly reminds watercraft owners to clean, drain and dry their craft when leaving lakes and before entering lakes to slow or stop the spread of invasive species.