By Gabe Licht
MAPLE PLAIN, MN Aquatic invasive species.
They are becoming a problem in lakes throughout the country. But, conservation officials are fighting back, including at Lake Independence in Maple Plain’s Baker Park.
The AIS in question is the zebra mussel. It has found its way into the local lake and people like Rich Brasch, the senior manager of water resources for the Three Rivers Park District, are doing something about it.
“We did a couple treatments last fall,” Brasch said.
Those treatments consisted of placing a curtain around the boat access, which is the mussels’ point of entry, and treating the area with copper.
“The copper basically affects the gill mechanism, their ability to take oxygen out of the water,” Brasch said.
Staff members were able to put the zebra mussels in cages to monitor them and learned the treatment resulted in a 70 percent mortality rate.
As for any effects on other aquatic organisms?
“I haven’t done any official toxicity work, but I scuba dived out there five or six times two-thirds through the last treatment and was finding native mussels that looked like they were in good shape in the treatment area,” Brasch said. “I was seeing yearling bluegills and crappies that weren’t any worse for wear.”
Three Rivers Park District received authorization for the treatment from the Minnesota Department of Natural Resources.
The DNR also approved the latest treatment method, which began May 21 and will take place through June 12.
“For the most recent treatments, we’re using potash,” Brasch said. “This is not stuff, at least at this point, available for everyone to use any time they want for zebra mussel control. It requires special regulatory approval.”
In this phase of treatment, park staff members have shut down half of the boat access so the curtain can stretch further down the shoreline, while also allowing boaters to access the lake. The curtain is expected to be moved from one section of the boat access to the other Monday or Tuesday.
“We’re trying to balance the public access issue, especially during peak access time,” Brasch said. “We’re concerned about striking the right balance.”
Based on results from the Memorial Day weekend, it appears that balance has been struck with the public.
“People figured out they need to use extra care putting in and taking out boats and it’s held up well,” Brasch said. “We really appreciate the public’s care and patience while we deal with this.”
It is unclear whether or not Lake Independence will undergo more treatment in the fall. Park staff will be working with the DNR to determine the best steps to move forward.
While fighting back against the zebra mussels that have already made their way to the lake, the park is also working to prevent more zebra mussels from entering the body of water.
The Three Rivers Park District currently has 75 to 80 AIS inspectors and Brasch said that number will grow to 110 to 130 inspectors during peak times.
While Brasch is hoping for the best, he is also being realistic regarding zebra mussels in the lake.
“I think it’s unrealistic to think we can eradicate them,” Brasch said. “We’re trying to make it as difficult as we possibly can for them to get established in other parts of the lake. If we had total eradication I would be very surprised.”