Reports of people finding zebra mussels in Lake L'Homme Dieu continue to stream in.
When Minnesota Department of Natural Resources surveyed the lake on June 26 after confirming that one zebra mussel had been found, it was like "looking for a needle in several hay stacks," said Luke Skinner, supervisor of the DNR's invasive species unit.
"But now, thanks to help from the public, we have hundreds of eyes out there looking for them," he said in a telephone interview with the Echo Press Wednesday. "Once the word got out, we've received quite a few reports scattered around the lake."
Zebra mussels can reproduce quickly, disrupting a lake's traditional food chain. They filter water, taking out plankton, algae and other nutrients that smaller fish eat. This, in turn, can reduce the amount of large fish.
Once zebra mussels get into a lake, there is no known method of controlling them, Skinner said.
How quickly they spread and the extent of the problems they cause varies, depending on the lake's chemical makeup and natural features.
"People need to be concerned," Skinner said. "The lake won't die but there will be impacts. People need to watch [for zebra mussels] closely and learn to adapt."
So far, the zebra mussels have been found only in Lake L'Homme Dieu, not in the other lakes that are part of the chain.
Based on what the DNR has discovered so far, Skinner believes the zebra mussels have been reproducing in Lake L'Homme Dieu for a year or two.
While the population of the zebra mussels is still low, it could change dramatically.
"We don't know how fast they'll grow," Skinner said. "On some lakes, the population increases quickly and on some lakes, it's slow."
When zebra mussels were found in Lake Mille Lacs in 2005, the numbers stayed low for three years and then in 2008, the population boomed, Skinner said. "Year four was the tipping point," he said.
The zebra mussels are expected to cause noticeable changes in Lake L'Homme Dieu.
Because the species filter so much water, the water clarity in the lake may improve, at least initially, Skinner said.
Clearer water would allow more sunlight to penetrate, leading to increased weed growth, especially in deeper areas of the lake.
A lake with zebra mussels in it can still provide good fishing opportunities, said Skinner. Lake Pepin, for instance, has had zebra mussels for nearly a decade and Mille Lacs is still yielding trophy fish.
Some game fish may behave differently, however, Skinner noted. He said that in one lake where zebra mussels were found, walleyes became more skittish during the day because the lake's improved clarity allowed the sunlight to penetrate more deeply. Anglers still found success during the night, he added.
Besides impacting fishing, zebra mussels can cause other problems, building up on rocks, logs, or any hard surface, including docks, boat lifts and swimming rafts.
Because their shells are sharp, zebra mussels can cause cuts at a beach.
Without any way of getting rid of the zebra mussels, the best thing for residents to do is to be aware of the problem.
"The number one thing is to minimize the spread," Skinner said.
That means reporting zebra mussel finds to the DNR and practicing extra precautions:
Inspect and remove all visible aquatic plants, animals and mud from boats, trailers and equipment such as anchors before leaving a water access.
Inspect and remove all visible aquatic plants, animals or mud from docks, boat lifts and swim rafts before transporting to another body of water.
Drain all water from boats - including live wells, bilges and bait buckets - before leaving a water access.
Spray or rinse boats with high pressure and/or hot water, or let them dry thoroughly for five days before transporting to another body of water.
DNR leaders are encouraged by the response and awareness lake users have shown since the zebra mussels were found.
The DNR launched an increased enforcement effort to prevent the spread of invasive species over the Fourth of July weekend. Conservation officers monitored activity on lakes L'Homme Dieu, Victoria and Carlos.
"I think it went very well," said Lieutenant Phil Meier. "The reception we received was very positive."
The DNR didn't find any zebra mussels on the boats, livewells and trailers they inspected - and they didn't expect to, Meier noted.
"Most everyone was aware of the problem and concerned and receptive to what we were doing there," he said.
Ironically, the DNR had already scheduled the invasive species enforcement before news broke about the zebra mussels in L'Homme Dieu.
"It was meant to be a pro-active effort but it turned out to be reactive," Meier said.
Still, Meier added, the DNR accomplished what it set out to do: Educate as many lake users as possible about how they can stop the spread of an invasive species.
WANT TO LEARN MORE?
The Lake L'Homme Dieu Association annual meeting is set for Saturday, July 18 at 9 a.m. at Good Shepherd Lutheran Church, Highway 29 North, Alexandria.
The open to the public meeting will feature a Department of Natural Resources expert who will talk about the zebra mussels that have been found in the lake.
IF YOU FIND ONE...
If lake users find a zebra mussel, they should take note of the specific location of where it was found and what it was attached to. They should then pull the mussel off and put it in a closed container filled with lake water. The container should then be refrigerated. Call Nathan Olson, a DNR invasive species specialist out of Fergus Falls, (218) 739-7576, extension 259.