Aquatic Invasive Species in Minnesota: Clean, Drain, Dispose Laws

Minnesota law requires three things every time you take a boat, or any other gear, out of a lake or river: clean off plants and invasive animals, drain all water with the plug pulled, and dispose of unwanted bait in the trash. These are not courtesy guidelines. They are in statute, they are enforced at roadside checks and boat ramps, and they carry civil penalties. This guide reflects the Minnesota DNR's rules and Minnesota Statutes chapter 84D as checked in October 2026.

What the law requires

The DNR sums it up as Clean, Drain, Dispose. Each step has specific legal content.

Clean

Before leaving a water access or shoreland property, remove all visible aquatic plants, zebra mussels and other prohibited invasive species from the boat, trailer, anchor and anything else that was in the water. It is illegal to transport aquatic plants or prohibited invasive species on a public road, dead or alive, and illegal to launch with them attached.

Note that the plant rule covers native plants too. An officer does not need to identify the species of weed hanging from your trailer bunk. Any aquatic plant is a violation.

Drain

• Drain the boat, motor, livewell, baitwell, bilge, ballast tanks and portable bait containers before leaving the access.
• Pull the drain plug, and keep it out, with all water-draining devices open, for the entire time the boat is on the road.
• Do not transport water from any Minnesota lake or river.

The plug rule is the one people trip on. You cannot arrive at a launch with the plug already in. Put it in at the ramp, after any inspection and before you back down. A reminder sticker near the trailer winch is worth having.

Dispose

• Unwanted minnows, leeches and worms go in the trash. Releasing bait into the water is illegal, and so is moving aquatic animals from one water body to another.
• The DNR's 2026 boating guide also lists dumping worms on the ground as illegal. Earthworms are not native to Minnesota's forests and damage them.
• Want to keep your minnows for tomorrow? Drain the lake water and refill the bucket with bottled or tap water. Bring a jug from home for this.

The 21-day rule for docks and lifts

A boat lift, dock, swim raft or associated equipment taken out of one water body may not go into another until at least 21 days have passed. Zebra mussels attached to a lift can survive for weeks out of water in damp conditions. This matters most when buying used equipment. Ask where it came from.

Recommended steps beyond the law

The DNR recommends these whenever possible, and especially if the boat was moored for more than 24 hours or came from water infested with zebra mussels or spiny waterflea:

• Dry for at least 5 days before using the boat in another water.
• Spray with high-pressure water.
• Rinse with very hot water: 120 degrees for at least 2 minutes, or 140 degrees for at least 10 seconds, kills zebra mussels and some other species.

Spots that hide plants and mussels: the anchor and its rope, the livewell, the transom well, rollers and bunks, the trailer axle, and the lower unit and prop. For personal watercraft, run the engine for a few seconds on the trailer to blow water out of the drive. Anglers who wade should clean waders and boots, and the DNR recommends avoiding felt soles.

The species behind the rules

Zebra mussels

Fingernail-sized mussels with striped, D-shaped shells that attach to any hard surface. The DNR records the first Minnesota confirmation in the Duluth-Superior harbor in 1989. A female produces 100,000 to 500,000 eggs a year, and the larvae, called veligers, are microscopic and drift in the water. That is why draining matters: you cannot see them in a livewell. Zebra mussels encrust docks and motors, clog water intakes, cut feet, kill native mussels and strip the plankton that young fish eat. They are well established in Mille Lacs, Minnetonka, much of the Brainerd and Alexandria areas and many Otter Tail County lakes. As of September 2026 the DNR lists about 5 percent of the state's lakes as infested.

Starry stonewort

A bushy, bright green macro-alga that looks like a rooted plant and forms dense mats. It was first confirmed in Minnesota in 2015 in Lake Koronis in Stearns County. Its calling card is a white, star-shaped bulbil about the size of a grain of rice. Those bulbils and small fragments cling to anchors, ropes and trailer bunks, and one is enough to start a new population. It is far less widespread than zebra mussels, which makes cleaning your gear especially worthwhile. It has turned up most often near public accesses.

Eurasian watermilfoil

A feathery, submerged plant that grows to the surface and forms mats thick enough to stop a propeller. It was found in Lake Minnetonka in 1987 and has since spread widely, mainly in the Twin Cities and central Minnesota. It spreads almost entirely by fragments, and a single piece carried on a trailer can root. It is easy to confuse with native northern watermilfoil, which is one reason the law bans transporting all aquatic plants.

Spiny waterflea

A predatory zooplankton, a quarter to five-eighths of an inch long, most of it a barbed tail. It reached Lake Superior by 1987, and DNR fisheries reports record it in Lake of the Woods since 2007 and Mille Lacs since 2009. It is also present in Rainy Lake, Vermilion and other border-country waters. Anglers notice it as gobs of bristly jelly on fishing line and downrigger cable. It eats the native zooplankton young fish depend on. Legally it is a regulated, not prohibited, species, but it may not be introduced into another water. Clean lines, nets and anchor ropes, and drain everything. Boundary Waters paddlers should take this one seriously when moving between lake chains.

Inspections and decontamination

Minnesota has run a watercraft inspection program since 1992. The DNR reports roughly 1,000 authorized inspectors, most of them hired by counties, cities, lake associations and tribal governments, performing more than 450,000 inspections a year.

What to expect:

• The inspector will look at and touch the hull, trailer and motor, and check compartments that hold water.
• They may ask where the boat was last used. You are not required to answer survey questions, and they will not deny launch based only on where you have been.
• They can deny launch if you refuse inspection, or if plants or invasive species are attached, until those are removed.
• If a decontamination unit is on site, they may require decontamination before you launch or leave. It usually takes a few minutes of hot or high-pressure water. The DNR does not charge for it, and it posts unit locations online.

Make it quick: arrive with the plug out, open the livewell lids, and have the bilge dry.

Conservation officers also run roadside check stations. Compliance is high. The DNR says that since 2017 more than 97 percent of boaters have arrived at inspections free of plants, animals, mud and water.

Penalties

Civil penalties under Minnesota Statutes 84D.13, as checked in 2026:

Violation	Civil penalty
Transporting aquatic plants	$100
Failing to drain, or transporting with the drain plug in	$100
Launching, or attempting to launch, with aquatic plants attached	$200
Transporting infested water without a permit	$200
Refusing a decontamination order	$250
Possessing or transporting a prohibited invasive species	$500
Launching with prohibited invasive species attached into uninfested water	$500

Penalties double for anyone with a prior violation. Some offenses are criminal: possessing or transporting prohibited invasive species is a misdemeanor, and refusing an officer's order to remove invasive species is a gross misdemeanor. Amounts are set by the Legislature and can change, so confirm with the DNR.

Infested waters and what the listing means

The DNR keeps an infested waters list naming each water body and the species involved. A listing does not close a lake. You can fish, swim and boat there normally. It does trigger extra restrictions on bait harvest, commercial fishing and water appropriation, and it is your cue to be thorough on the way out.

If you find something suspicious on a lake not listed for it, note the exact location, take a photo or keep the specimen, and contact the DNR at 888-646-6367.

Bottom line

• Plug out, water out, weeds off, every time you leave the water. Plug stays out on the road.
• Bait goes in the trash or home in tap water, never back in the lake.
• Five days of drying or a hot-water rinse between lakes is not required, but it is what actually stops the species you cannot see.