Three species (
M. aquaticum,
M. heterophyllum and
M. spicatum) have aggressively invaded lakes, natural waterways and irrigation canals in North America. The U.S. states most affected have implemented control plans. The
Tennessee Valley Authority detected milfoil in its waters in the 1960s. It discounted milfoil's value as a food or feedstock and fought it with chemicals and lowering of water levels. It suggested that water lilies (
Nelumbo lutea) might deny it sunlight. The widespread invasive
Eurasian watermilfoil (
M. spicatum) is often controlled with
herbicide containing
diquat dibromide. Control can also be done through careful mechanical management, such as with lake mowers,{{cite web Mechanical management can include the use of a long-reach lake rake or aquatic weed razor blade tool. Using these tools is similar to lawn work. These tools are most effective before seeds set. Infestations can be prevented through the use of a Weed Roller or a LakeMaid. These are automated and unattended machines. Permits may be required by various states. In 2007, Professor Sallie Sheldon of
Middlebury College reported that an aquatic
weevil (
Euhrychiopsis lecontei), which eats nothing but milfoil, was an effective weapon against it. Since roughly 2000, invasive milfoils have been managed by hand-harvesting. Several organizations in the New England states have undertaken successful lake-wide hand-harvesting management programs. Periodic maintenance is necessary; the species cannot be completely eradicated once established, but it can be reduced to manageable levels. Well-trained divers with proper techniques have effectively controlled milfoil and maintained lakes, such as in the Adirondack Park in Northern New York where chemicals, mechanical harvesters, and other management techniques are banned as disruptive. == Taxonomy ==