A simple definition of an aquatic weed is a plant that grows (usually too densely) in an area such that it hinders the usefulness or enjoyment of that area. Some common examples of aquatic plants that can become weeds are the water milfoils, ribbon weeds, and pondweeds. They may grow in ponds, lakes, streams, rivers, navigation channels, and seashores, and the growth may be due to a variety of factors such as excess nutrients in the water or the introduction of rapidly-growing exotic species. The problems caused by aquatic weeds are many, ranging from unsightly growth and nuisance odors to clogging of waterways, damage to shipping and underwater equipment, and impairment of water quality.

It is difficult and usually unnecessary to eliminate weeds completely from a lake or stream. Therefore, aquatic weed control programs usually focus on controlling and maintaining the prevalence of the...