Mechanically Controlling Aquatic Weeds

Aquatic weeds are a nuisance in lakes, ponds, and other bodies of water. They can disrupt the natural ecosystem and limit recreational activities such as fishing, swimming, and boating. Communities also rely on their waterbodies for the collection of stormwater, but overgrown weeds can block and damage this important equipment, increasing the risk of dangerous flooding. Though aquatic herbicides can be helpful tools to quickly eliminate undesirable vegetation, many stakeholders prefer a natural approach. Mechanical removal is an alternative solution that can be used to control nuisance weeds and restore the waterbody as a recreational and functional asset. 

Aquatic experts rely on two types of mechanical equipment – hydro-rakes and harvesters. Before choosing the method of control, it is important to identify the target weed species. Professionals are trained in the proper identification of aquatic weeds, many of which resemble beneficial native plants. From there, experts can determine which equipment is best suited to remove the weeds.

Eurasian Watermilfoil is a fast-growing weed with long feathery leaves. Each plant can grow up to 20 feet in length and aggressively outcompete native species. Eurasian Watermilfoil is considered one of the most problematic invasive aquatic plants in the United States, and can cause significant damage by clogging water intake pipes, impeding the flow of water, and tangling boat motors.

Hydrilla is an invasive aquatic plant with dense branching stems that can grow up to 20 feet long. Each stem is covered in small, pointed leaves with serrated edges, giving them a saw-toothed appearance. Hydrilla is a highly adaptable weed that can grow in a variety of water conditions, including slow-moving or stagnant water, and has been known to entangle and even drown swimmers.

Invasive Curly-Leaf Pondweed has glossy, dark green leaves that are typically 2-4 inches long with wavy edges that give them a curly appearance. The leaves are arranged alternately on the stem, which can grow up to 10 feet in length. Curly-Leaf Pondweed is extremely fast-growing and can cause significant damage to native ecosystems and essential stormwater infrastructure.

Other common submersed weeds include Fanwort, Mudmat, and Variable Milfoil.

Giant Salvinia is an invasive floating fern composed of chain-like oblong leaves with sharp hairs. The aquatic weed can quickly form dense floating mats that block sunlight and prevent the transfer of oxygen on the surface of the water. Native plants and animals can suffer and die-off as a result.

Water Hyacinth has large, round leaves with a shiny, waxy surface. Though it is a floating weed, it produces long, feathery roots that can extend several feet below the water’s surface. Water Hyacinth is extremely invasive and can overtake an entire waterbody without intervention.

Water Chestnut can be identified by its triangular serrated floating leaves arranged in a rosette pattern that radiates from a central stalk. Each rosette can produce up to twenty spiked nutlets, which allow populations to explode in a few short seasons.  

Other common floating weeds include Water Lettuce, Duckweed, and Yellow Floating Heart. 

Controlling aquatic weeds can be costly and time-consuming – and can cause significant stress to residents and community leaders. Through an Annual Management Program, professional monitoring can give stakeholders peace of mind that any new infestation will be identified and managed early on. It is also recommended to inspect and clean boats and water equipment before and after a day on the water. Many weeds reproduce via fragmentation, meaning small pieces can quickly populate a new ecosystem.