Utah's invasive mussel defenses: what inspections, dip tanks and a new zebra mussel find show

Utah Division of Wildlife Resources biologists collected a live adult zebra mussel in the Colorado River below the Westwater Recreation Area on Sept. 22. Tests confirmed it on Oct. 7, about a month after the agency confirmed zebra mussel DNA on the Utah side of the river. ^[1]

Zebra and quagga mussels are different species. Lake Powell's infestation is quagga mussels; the river find is a zebra mussel, which the division calls an emerging threat in the Upper Colorado River Basin after an established infestation was documented near Loma, Colo., in 2025. ^[1][2]

The DNA came from an automatic sampler near the Potash Boat Ramp, about 14 river miles below Moab. Four of 22 daily samples taken in June and July tested positive. The division says it is working with federal agencies to learn the status of zebra mussels in the river within Utah. ^[1]

Why the boat gets inspected

Adult mussels attach to hard surfaces, including boat hulls. Their larvae, called veligers, are microscopic and drift in the water for up to a month before settling, according to Utah State University Extension. Water held inside a boat can carry them. ^[3]

The mussels filter large amounts of water, which depletes the plankton native fish and invertebrates feed on. They also clog water lines and engine cooling systems. ^[1][3]

At Lake Powell, containment

The first adult quagga mussels were found in Lake Powell in March 2013. A science panel convened by Glen Canyon National Recreation Area concluded there is no known feasible way to eradicate them from the lake, so the park's focus shifted from prevention to containment. ^[2]

The park's analysis ranked boats kept in slips or moorings as the highest-risk way to spread adult mussels, and boats that come and go as lower risk. The Park Service says it has no authority to enforce state containment laws on boats leaving the lake; state officers do. ^[2]

What boaters must do

Every boater in Utah, resident or not, including paddleboarders and kayakers, must take the division's annual mussel-aware boater course and carry proof in the launch vehicle. Owners of motorized boats must also enroll in the aquatic invasive species program, for $20 a year for residents and $25 for nonresidents. Boaters must stop at any operating inspection station. ^[4]

A boat arriving from another state or country, or one used on an infested water such as Lake Powell in the past 30 days, must either go through the full clean, drain and dry process or get a professional decontamination before launching anywhere in Utah. ^[4]

If the inspection station at Lake Powell is closed, the owner is still legally responsible for cleaning and draining the boat and towing it with all drain plugs removed. ^[4]

Dip tanks

A dip tank is a heated tank set in the ground. The boat stays on its trailer, backs in, and its own engine and pumps run hot water through its systems. In its 2023 annual report, the division said dip tanks had cut decontamination of a complex surf boat from more than an hour to roughly 15 minutes. That is the agency's figure, not an independent measurement. ^[5]

As of Sept. 8, five dip tanks were operating: at Lake Powell's Stateline Launch Ramp at Wahweap and at Bullfrog Marina, and at Utah Lake, Sand Hollow and Willard Bay state parks. The division said two more were scheduled to open this year. ^[6]

The Legislature's 2026 budget includes $4 million in one-time General Fund money to buy and install dip tanks around the state, to speed decontamination and improve compliance. The budget summary does not say where or when they will be installed. ^[7]

A 2023 study in Scientific Reports, testing six invasive species from Ontario including zebra mussels, found that hot water followed by air-drying was more effective than either alone against all species tested. It was not a test of Utah's equipment, and it did not include quagga mussels. ^[8]

What the numbers measure

Over the Friday-to-Monday Labor Day weekend, inspectors from the division, Utah State Parks, Arizona Game and Fish, the Park Service and the Department of Natural Resources inspected 9,418 boats statewide and performed 154 decontaminations. Of those, 440 inspections and 44 decontaminations were at Lake Powell-area stations. ^[6]

Those figures count inspections, not separate boats, and they cover one holiday weekend. A decontamination is a response to risk, not proof that an infestation was prevented. ^[6]

A closer measure of interceptions is the number of boats found carrying mussels. In 2023, through Dec. 1, the division reported 269,362 inspections and 6,642 decontaminations, and said more than 180 inspected boats had mussels attached or inside their systems. ^[5]