Nilan Reservoir Eurasian Watermilfoil Decision Notice
Nov 9, 2021 10:56 AM
The department proposed to control a newly discovered population of Eurasian watermilfoil (EWM)
(Myriophyllum spicatum) in a. small bay in Nilan Reservoir near Augusta, MT. This is a highly invasive aquatic plant, and this is the first detection of EWM in this basin. This is a small population of 1.15 acres with a current water depth of 3 to 4 feet. Treatment would involve the application of fluridone, an aquatically registered herbicide along with installation of a curtain to separate the small bay from the rest of the lake and reduce water exchange.
After review of this proposal and public comment, FWP will apply the aquatically labeled herbicide, fluridone, to eradicate the small 1.15- acre patch of Eurasian watermilfoil. The herbicide application will begin November 10, 2021 in cooperation with the Department Natural Resources and Conservation and Nilan Water Users Association. There will be a minimum of a 45-day exposure time ending at the earliest December 25, 2021. The bay will be curtained off to prevent water exchange with the remaining lake and will stay separated for the entirety of the winter since the curtain will be frozen in place by the end of the 45-day exposure time.