Many methods have been tried in the United States and Canada to contain or eliminate Eurasian watermilfoil. The control methods can be classified as chemical or physical. Biological control methods are still in the research and development stage. Chemical control methods have been based primarily on the use of 2,4-D because the plant is highly susceptible to it. There may also be adverse effects upon the environment, such as fish kills, increased algal growth, or contamination of public water supply.
Mechanical harvesters cut and remove most of the plant and deposit the debris on land.
Diver-operated dredges operate like underwater vacuum cleaners to remove plants etc. Drawdown in winter exposes the plants to below freezing temperatures. A promising new approach, still in the testing stage in 1985, involves the use of high intensity ultrasound to kill the plants in situ. The majority of the respondents to the survey rated Eurasian watermilfoil to be a moderate to severe problem of a widespread nature that is still spreading. One respondent felt that it has stabilized in many Ontario wetlands.