DNR taking further steps to reduce risk of starry stonewort spread

WASHINGTON, D.C. – October 5, 2015 – (RealEstateRama) — The Minnesota Department of Natural Resources is taking additional measures in response to the discovery of starry stonewart in Lake Koronis, Stearns County. The DNR will treat the invasive algae in front of the main public access at Lake Koronis, as part of an expanded effort to reduce the risk that it will spread to other bodies of water.

The treatment will be monitored for its effectiveness in reducing the existing mats of starry stonewort, making it less likely the algae will be picked up by boats as they exit the access. Lake Koronis and Mud Lake, connected to Koronis, are the only Minnesota water bodies with confirmed infestations of starry stonewort.

Treatment is the latest step in a series of actions the DNR is taking in conjunction with local governments:

Shortly after the infestation was confirmed, the DNR worked with the North Fork Crow Watershed District to increase inspector hours at the DNR access to 10 hours per day, seven days per week. (Note: Mud Lake does not have public accesses.)

• The DNR surveyed all of Lake Koronis, and the results showed starry stonewort across approximately 250 acres and scattered around other parts of the 3,000-acre lake.
• The DNR has surveyed other lakes in the area. Starry stonewort has not been found in any other nearby water body or reported anywhere else in the state. Surveys are ongoing for lakes that are popular destinations for boaters after they leave Lake Koronis.
• The DNR is working closely with local governments to provide continued, consolidated access to the lake while the DNR public access area is treated.

To make the treatment as effective as possible and to monitor the treatment area, the DNR will temporarily close the main Lake Koronis public access off Highway 55. Treatment is scheduled for early next week with the herbicides Cutrine-ultra and Hydrothol 191. Cutrine-ultra is a copper-based herbicide, and Hydrothol 191 is based on endothall, which is commonly used to control aquatic plants. The access will remain temporarily closed until the lake is ice-covered in late fall. The DNR will continue to work with local governments over the winter and use information gathered from this initial treatment to develop a long-term strategy for this species.

The city of Paynesville, Paynesville Township, and Stearns and Meeker counties manage the other four accesses on the lake. They are working with the DNR to provide boater access and coordinate watercraft inspections at those accesses.

“The goal of this treatment to knock back the starry stonewort from the DNR access area, in order to reduce the risk of spread when boats leave the access,” said Ann Pierce, section manager, DNR Ecological and Water Resources Division.

“We want to thank the many partner organizations for helping with this effort to prevent the spread and manage the infestation of starry stonewort in Lake Koronis,” Pierce said. “They include the North Fork Crow Watershed District, the Koronis Lake Association, Stearns County Lake Associations, Stearns and Meeker Counties, the city of Paynesville, and Paynesville Township, the U.S. Fish and Wildlife Service, and the Minnesota Aquatic Invasive Species Resource Center.”

Starry stonewort was first discovered in the U.S. in the St. Lawrence River in 1978 and has spread into lakes in the northeastern U.S. Starry stonewort was also confirmed in Wisconsin in 2014 and has been reported in Michigan lakes for more than a decade. The invasive species was likely brought to Lake Koronis by lake users who transported fragments of the plant from an infested body of water.

Starry stonewort are grass-like algae, which produce dense mats that interfere with recreational use, choke out native plants, and have other impacts that alter lake habitat.

People spread aquatic invasive species, and people can reduce their spread. Vigilance and compliance with aquatic invasive species laws is required every time a boat or other equipment is taken out of a lake. The DNR reminds boaters and anglers to follow Minnesota laws to prevent the spread of aquatic invasive species and help protect Minnesota waters:

• Clean aquatic plants and animals from watercraft.
• Drain all water by removing drain plugs and keep drain plugs out while transporting watercraft.
• Dispose of unwanted bait in the trash.

More information, including a 30-second public service announcement about stopping the spread of aquatic invasive species, is available on the aquatic invasive species Web page.