Aquatic Plant Management

The Western Aquatic Plant Management Society

Description of Method

Mechanical weed cutters cut aquatic plants several feet below the water's surface. Unlike harvesting, cut plants are not collected while the machinery operates. There are several versions of underwater weed cutters commercially available, including:

Hand-held, battery- powered cutters
Portable, boat-mounted cutting units
Specialized barge-like cutting machines

Cutting is generally performed during the summer when plants are near the surface.

Battery-Operated, Hand-held Cutters

Battery Operated Cutting Tool A stainless steel underwater cutting blade works like a hedge trimmer to cut aquatic plants. An adjustable shaft allows the operator to reach to twelve feet below the water's surface and cut a four foot swath. It generally takes about an hour to clear an average waterfront lot of weed growth.

Portable Boat-mounted Cutters

A portable underwater cutting unit can be installed on a 14-foot or longer boat. A boat-mounted under water cutter cuts a seven-foot swath four feet below the water's surface. About one acre of plants per hour can be cleared using this device.

Specialized Underwater Cutters

Hockney cutter Specialized underwater weed cutters can cut weeds in water as shallow as ten inches and as deep as five feet. The main sickle will cut a swath ten feet wide. Specialized cutters can cut about 12 acres per day.

Cleanup

Cutting generates floating plants and fragments. It is important to remove all plants and fragments from the water to prevent them from rerooting or drifting onshore. Cleanup can be accomplished using a weed rake. Specially designed nets should be used when using boat-mounted and larger underwater cutters. The time needed for cleanup depends on the density and types of plants and the amount of acreage cut.

Advantages

Cutting creates immediate open areas of water.
Mechanical underwater cutters can work in shallow waters not accessible to larger harvesters.
Hand-held equipment can easily be maneuvered around docks and marina areas.
Habitat for fish and other organisms is retained if the plants are not cut too short.
Hand-held cutters are easily transportable.
Prices of mechanical cutters are substantially lower than harvesters.
Renting hand-held cutters at equipment rental stores may be possible.

Disadvantages

Cutting is similar to mowing a lawn-the plants grow back and will likely need to be cut several times during the growing season.
Some plants are difficult to cut.
Cutting creates plant fragments which may enhance the spread of invasive plants such as milfoil. These fragments may also drift onshore and decompose.
Floating plants need to be removed from the water.

Permits

Permits are required for many types of projects in lakes and streams. Check with your state and local jurisdictions before proceeding with your project.

Costs

The price of hand-held cutters ranges from $150 to $1,300, plus accessories.
Portable boat-mounted cutting units cost from $400 to $3,000.
Specialized underwater cutters cost about $11,000.