Striped and Severe: Zebra Mussels Infest Balsam Lake

Katelin Anderson and Colton Sorensen are water quality specialists for the Polk County Land and Water Resources Department. Sorensen has been a water quality specialist for nearly three years and has lived in the area all his life. Anderson has been with the Polk County Land and Water Resources Department for over 10 years and has served as both a water quality specialist and Information & Education Coordinator.

In June, a resident called the DNR to report a potential Zebra Mussel he had found on the Northern bay of Balsam Lake. After confirming the sample to be a Zebra Mussel, the water quality specialists, along with the DNR, surveyed the water for any other signs of the species. Unable to find any adults, the team conducted “veliger tows,” a collection process through which the “immature,” free-floating, microscopic mussels could be collected and analyzed. Sorensen recalled the peculiar results of the sampling. “We sent that back to a lab, and that came back with one veliger, which is kind of a needle in a haystack. One female adult zebra mussel can produce up to a million [veligers] in a summer, so the odds that we were able to find just one is interesting.”

The DNR requires three distinct locations, or three distinct age classes, of invasive species activity for the lake to be considered “infested.” With this microscopic sliver of Zebra Mussel activity present, it became even more crucial to determine the full extent of their occupation. But as the months went on, the veliger became even more of an oddity. “The whole summer went by with a lot of people looking, just not finding anything.”

But in late September and early October, the teams’ sampling efforts exploded with activity. “We pulled a plate sampler from the gentleman’s dock who found the first one and found 22 zebra mussels on it.” The findings sparked the specialists to survey the lake’s hotspot locations for mussel activity. “We found the mussels at an additional five locations on the lake, so then it was pretty well confirmed that they’re in there.”

The zebra mussels will alter the ecosystem of the lake in several ways as they continue to expand. “It makes more habitats for some fish, but also crowds out natives and moves fish populations.” The mussels remove plankton from the lake, which will increase water clarity and promote plant growth as more sunlight hits the water. However, this clarity is not without its drawbacks. “The water will eventually get cleaner, but the flipside of that is that they don’t feed on blue green algae, which are the toxin-producing gross scums.”

One of the primary focuses of the specialists is containing the species and preventing spread to the surrounding lakes. “We did a lot of outreach about where to look. On docks, inside tires.” The mussels are not as easy to spot as one may think, and often require very careful inspection of aquatic equipment. “A full adult is about the size of your fingernail.”

Anderson explained that it is much more feasible to consider containment, rather than complete elimination, of the zebra mussels. “For Balsam, we’re probably never going to get rid of them. Too many acres of water and flowing water with the inlet/outlet. The treatment is so

expensive when you have that much water. Getting rid of them is probably just not feasible, or not allowed by DNR.”

As Sorensen elaborated, “For Balsam, you’re in the millions-of-dollars range if you’re going to do a large-scale treatment.” Beyond the exorbitant cost, the large-scale treatment options would likely have negative effects on the overall aquatic ecosystem. “There’s no official permitted zebra mussel technique that the DNR allows. A lot of non-target species would be affected. Basically, if it goes wrong, you could kill the entire lake.”

Anderson unfolded the efforts of the lake group to contain the ecosystem. “Balsam is applying for a grant to do decontamination stations at all of their landings. They are definitely on top of trying to prevent the spread of invasive species.” The group will hopefully receive grant approval in winter or early spring.

The team is eager to get the word out on how lakeside residents and recreational users can help keep the water clean. One of the best methods to help reduce invasive species is to decontaminate docks, boats, and other recreation equipment before and after touching with the water. Spraying the equipment with bleach solution or leaving it to dry for five days will kill the mussels and veligers.

A positive step forward for the team’s public education efforts is an inflow of reports and concern from the public. “This year, we’ve had some dock service providers report [invasive species] on Balsam. That’s a pretty new program—last year was the first year that we worked to get info out to that group.” As public education and decontamination efforts continue to expand, Balsam Lake faces its invaders with an adept defense of public and professional support.