Efforts made by the Department of Natural Resources (DNR) may soon make Christmas Lake in Shorewood, Minnesota free of an aquatic threat.
On Friday, DNR pumped a special chemical to kill the remaining zebra mussels in the lake following two prior treatments that aimed to eliminate infestation of the invasive species before this become more widespread.
The fresh-water thriving zebra mussel was originally found in the lakes of southern Russia but the species was accidentally introduced to different countries worldwide, where they have become an invasive species particularly in North America, Spain, Italy and Great Britain. The creatures are known to disrupt the ecosystem as well as damage waterways, water vessels and pose problems to water treatment plants.
In August this year, Minnesota DNR found a small number of zebra mussels in the northwest corner of the lake and subsequently treated the area with Zequanox, a substance composed of dead bacteria and later, using a copper-based chemical. Although the treatments appeared to be successful, the infestation was later found to be larger.
On Dec. 19, the DNR proceeded with its third treatment which involved injecting 1,000 pounds of potassium chloride, also known as liquid potash, under the ice near to where the zebra mussels were found earlier this year.
The treatment cost the DNR $1,500 for the 40,000-square-foot affected area and marks the third time that the chemical was used to control zebra mussels in U.S. because potash is not a federally registered pesticide.
DNR needed to get an authorization from the U.S. Environmental Protection Agency as well as had the chemical registered as a pesticide with the Minnesota Department of Agriculture before it could proceed with the treatment.
"We're trying all available options at Christmas Lake as the zebra mussel infestation was isolated to a small area of the lake," said DNR invasive species specialist Keegan Lund. "Most importantly, we're learning a lot about new treatment methods for zebra mussels that have not been used before in lakes."
The Minnesota Pollution Control Agency, which reviewed the treatment plan, did not also find immediate concerns over water quality. DNR said that potash does not affect the fishes but kills the zebra mussels by getting in the way of their oxygen supply.
"It interferes with the gill respiration of specifically, mollusks. It doesn't target fish or any other aquatic organisms," Lund said.
The DNR said that if the treatment at Christmas Lake is successful, it will be the first time that the invasive species have been eliminated from a water body in Minnesota.
