Friday, October 23, 2015

Despite treatment, 16 zebra mussels confirmed in Christmas Lake

Agencies learning about management options

Despite aggressive treatment, 16 zebra mussels have been confirmed across a wide area of Christmas Lake in Shorewood, according to the Minnesota Department of Natural Resources. The spatial distribution and age of the mussels found indicate that a reproducing population is established and further treatment would not be effective. While the agencies involved in the treatment project are disappointed, they say the information gained from the effort was worthwhile and will be used for future treatments in other bodies of water.

Although no zebra mussels were found in extensive dive searches of the lake as recently as last month, a lake service business reported finding one zebra mussel on a dock earlier this week. Divers with the DNR and the Minnehaha Creek Watershed District found the invasive species on docks and boat lifts in an inspection that followed the initial report.

"These findings demonstrate the challenges of monitoring and treating zebra mussels," said Keegan Lund, DNR invasive species specialist. "None of these newly discovered zebra mussels were found in the area of Christmas Lake that was treated earlier this year," Lund noted, "but most of those we found were juveniles. That tells us reproduction has occurred and this population is established. Because zebra mussels are scattered across the lake and reproducing, current management options are not feasible.

"We're working with the Christmas Lake Homeowner's Association, the Minnehaha Creek Watershed District, and the Minnesota Aquatic Invasive Species Research Center to continue our assessment," Lund said. "What we learn will inform future rapid response treatments and pilot projects. The DNR appreciates the valuable contributions all partners have made to this project."

The first zebra mussel in the recent Christmas Lake discoveries was found on a dock by a lake service provider who was removing the equipment from the water. This find is a reminder that this time of year, when water-related equipment is being removed, is an especially important time to check docks, lifts and other equipment for zebra mussels. By law, docks and lifts must also dry for at least 21 days before putting them into another body of water, whether they are coming from an infested lake or not.

"There is a common misconception that zebra mussels 'are everywhere' and that their spread is inevitable. The reality is, zebra mussels have been confirmed in less than two percent of Minnesota lakes, and more Minnesotans than ever before know and follow invasive species laws," Lund said. "People spread zebra mussels, and people can prevent the spread."

For more information on aquatic invasive species prevention and how to report a suspected infestation, visit

No comments: