Minnesota lake first in nation to use new product to kill zebra mussels

A small Minnesota lake is on the forefront of the national effort to kill off the zebra mussels that threaten lakes and rivers around the country.

Christmas Lake in Shorewood became the first in the nation Monday to use a new technology that utilizes dead bacterial cells to eradicate the razor-shelled creatures that can damage boat motors, slice swimmers' feet and threaten fish populations. The outcome could be a defining turning point in what has been a losing battle to control an invasive species that has spread to 29 states.

"This is history," said Dan Molloy, a New York research scientist who developed the product, called Zequanox, and has advised local leaders. "It's the first attempt to solve the zebra mussel problem in the world. And it's got a shot at it."

Minnesota officials have been intensifying efforts the past few years to slow the spread of numerous aquatic invasive species. These exotic mussels have spread around the state's lakes by catching rides on boats and other watercraft. So far, efforts have largely focused on education and prevention, increased boat inspections and restrictions.

For the first time, wildlife officials are going on the offensive. The work on Christmas Lake finished Monday, and now researchers from the U.S. Geological Survey will test different applications and concentrations of Zequanox on neighboring Lake Minnetonka. Before now, the product had only been used in small experiments or to reduce zebra mussels in power plant water pipes.

"If it works, it will be a huge success story," said Keegan Lund, an invasive species specialist with the Department of Natural Resources.

Zebra mussels have become the central focus in the fight to control the spread of aquatic invasive species. Along with being a nuisance to boaters and swimmers, zebra mussels can alter habitat for fish and insects. They can quickly proliferate by the millions once they are transported to a lake. Across Minnesota, zebra mussels have already infected nearly 200 waterways, such as Lake Minnetonka.

With Christmas Lake located so close to the massive lake, the local lake association has taken aggressive and sometimes controversial measures to prevent infestation, such as installing a gate at the only public access to prevent boaters from using it when inspectors aren't there.

In August, four tiny zebra mussels were discovered near the boat launch, part of an estimated 5,000 juvenile zebra mussels later discovered in the lake as part of the Minnehaha Creek Watershed District's early detection monitoring program.

The federal government just approved Zequanox for use in lakes in July. The product is made from dead bacteria that kill zebra mussels when they eat it. For the first major trial, experts needed a lake that wasn't fully infested.

In Christmas Lake, experts were able to detect the infestation early and prevent it from spreading by sectioning off the bay next to the boat launch and closing the public access to the estimated 800 boaters who use it each year.

"If it had been on the whole lake, we probably would have said, 'Good luck, you got them,' " said Craig Dawson, the aquatic invasive species director for the Watershed District. But "it's been well worth the effort. The information will be valuable for others."

On Monday, crews boarded a boat and, with gloves and masks, they sprayed the biological pesticide into the lake, turning the water a cloudy white color in the 50-foot by 60-foot area cordoned off from the rest of the lake. Officials from other counties and park districts watched the process.

But there are still questions. Wildlife officials want to know how will it affect small minnows in the lake and whether it will kill off 100 percent of the zebra mussels. Crews will monitor the lake daily to answer those questions, but won't know if the effort was successful for two weeks.

Even then, they will be checking back next spring to see if the mussels return.

If they are successful, it is not a guarantee for other lakes like Minnetonka. Experts say it is too difficult and costly to kill off zebra mussels on entire lakes, particularly large ones. On Christmas Lake, the Minnehaha Creek Watershed District paid $2,500 on equipment and the DNR spent $6,800 for Zequanox.

If all the zebra mussels aren't destroyed, the DNR is looking into federal approval for a chemical treatment, which has been used in places like Winnipeg and Virginia.

No matter the result, the lake will offer groundbreaking answers to questions about the technology and how it can help with a growing national problem.

"This is the best chance we have of removing zebra mussels from lakes," Dawson said. "We know there's no 100 percent guarantee with the product, but it's the best we can do."

Kelly Smith • 612-673-4141

Twitter: @kellystrib