Clear Lake City Council approves support for DNR efforts to eradicate Eurasian watermilfoil

CLEAR LAKE — Clear Lake’s City Council last night approved signing a letter of support for the Iowa Department of Natural Resources efforts to eradicate Eurasian watermilfoil from the lake with herbicide treatments.

Eurasian watermilfoil is a non-native submersed, rooted aquatic plant that is native to Europe and Asia that impacts an aquatic ecosystem by reducing the sunlight availability, which reduces native aquatic plant germination and diversity. Eurasian watermilfoil was first identified in Clear Lake in the late fall of 2023, and aquatic vegetation surveys of the lake were conducted last year. Two large spot treatments were also completed last year to reduce the plant’s abundance.

CLEAR Project coordinator Joel Schwichtenberg says the DNR has done similar successful treatments to combat Eurasian watermilfoil.  “Regionally, in the Black and Blue Pit of Mason City, as well as a private pond downstream of Black Pit have been treated with the same herbicide that is intended for Clear Lake, none of which have required an addition of herbicide following that initial application. Throughout Iowa, about a dozen other lakes that have been treated have shown no evidence of regrowth.”

The initial treatment cost is estimated to be about $280,000, which will be covered by the DNR. Additional treatments may be needed after the initial treatment during the 90-to-120 days required concentration period. Those additional treatments would cost about $170,000, which would be covered through contributions by the cities of Clear Lake and Ventura, Cerro Gordo County, and donations made to the project through the Association for the Preservation of Clear Lake.

Schwictenberg hopes additional treatments won’t be needed.  “I have since received budget requests and filed and approved from the City of Ventura, the Cerro Gordo County Board of Supervisors, as well as the Association for the Preservation of Clear Lake to partner and provide funding for the concentration testing and monitoring, as well as an herbicide reserve. This reserve will be crucial in the event that the initial application does not maintain the concentration and is required and needed to maintain that concentration necessary to appropriately treat the Eurasian watermilfoil.”

As part of their letter of support for the DNR, the council approved a financial commitment of up to $85,000 for additional treatments if necessary.