Beaver Lake Eurasian Watermilfoil Monitoring and Control

Eurasian Watermilfoil Found in Beaver Lake
In October 2011, Eurasian Watermilfoil (EWM) was discovered near the boat ramp on Beaver Lake in Whitefish, Montana. An Aquatic Invasive Species (AIS) response team—of which the Whitefish Lake Institute (WLI) was a member—responded to the discovery for further investigation. Bottom barriers were placed over the identified patch and a control/eradication plan was developed by a multiple agency workgroup in which the City of Whitefish and WLI participated.

Why We're Concerned
If left untreated, EWM forms dense mats of vegetation on the surface of the water that can interfere with recreational activities such as fishing, swimming, and boating, and that threatens the health of the water body. The resulting effect can be the loss of recreational use, decline in ecosystem health, and a decrease in lakefront property values. EWM reproduces successfully and very rapidly, making it a threat to any water body it invades.

Ongoing Efforts
Since 2012, WLI and the City of Whitefish have taken the lead in addressing the EWM issue at Beaver Lake. As part of the Whitefish AIS Management Plan, WLI coordinated a suction dredging operation to eradicate plants. In 2012, 23.5 pounds of EWM was removed. The program has proven successful with fewer plants found each year. This atypical AIS success story is the result of very early detection coupled with rapid and aggressive eradication techniques. Because of the real threat to Whitefish Lake and the watershed, Montana Fish, Wildlife, & Parks—in partnership with WLI—will continue monitoring and suction dredging until there is confidence that the EWM has been eradicated.

Protecting Whitefish Lake from EWM and other AIS
Due to the close proximity of Beaver Lake to Whitefish Lake, WLI deploys a turbidity curtain to prevent fragments from moving downstream toward the lake. The curtain—provided by the Flathead Lakers—is installed at the outlet of Beaver Lake where Beaver Creek begins to flow. WLI also partnered with the Flathead Basin Commission to conduct a 100-point AIS presence/absence survey on Whitefish Lake. No EWM or other invasive plant species were found. EWM efforts will continue in the future.

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