Aquatic Invasive Species Management

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Prevent the transport of aquatic invasive species to Yellowstone by making sure you clean, drain, and dry your boat before you arrive.

Aquatic invasive species (AIS) pose a grave and growing threat to the Greater Yellowstone Ecosystem. An AIS is a freshwater or marine organism that has spread or been introduced beyond its native range and is either causing harm or has the potential to cause harm. AIS can quickly and drastically transform habitats and food chains, causing permanent declines in fish and food resources for native wildlife. At least eight AIS already exist in Yellowstone's waters: New Zealand mud snail, red-rimmed melania, five nonnative fish, and whirling disease.

Our Goals

We promote aquatic invasive species awareness and communicate how to stop them.

Using Clean, Drain, Dry procedures is an effective way to stop the spread of AIS. Some invasive species, such as mussels, can survive as long as 30 days out of water.

We work with partners to inspect incoming watercraft for aquatic invasive species.

Yellowstone National Park, Grand Teton National Park, and surrounding states aim to inspect all boats entering the region before launch to maximize protection of park and surrounding waters and minimize inconvenience to visitors.

We monitor Yellowstone waters for aquatic invasive species.

Early detection of AIS, including the use of environmental DNA surveys, can prevent the accidental spread to other areas.

Preventing Aquatic Invasive Species

Prevention is the best tool in AIS management. Once an AIS is established in an area, it’s usually impossible to eradicate, or the eradication methods come with serious environmental consequences. Also, controlling an established population is difficult and expensive. Yellowstone works to prevent new AIS from entering the park through public education and awareness, a permit and inspection process, and aquatic resource monitoring.
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Clean, drain, and dry your equipment before visiting Yellowstone.

Stop Aquatic Hitchhikers Logo

Education & Awareness

The Stop Aquatic Hitchhikers! national education campaign was launched by the Aquatic Nuisance Species Task Force in 2002. The goals of the campaign are to raise awareness, change behaviors, and build community capacity to stop the spread of aquatic invasive species across the United States and beyond. Currently, there is a network of over 1,400 campaign partners across the country.

As a proud campaign partner, Yellowstone empowers recreational users of aquatic resources to “Clean, Drain and Dry all watercraft, trailer, motors, and gear every time, everywhere.”
Yellowstone AIS seal
A 30-day dry time, seal, and inspection receipt are required for all sailboats and certain complex motorized boats (inboard, inboard/outboard, or inboard jet drives).

Permits & Inspections

Yellowstone employs a team dedicated to inspecting all watercraft before launch. In combination with the efforts of responsible visitors who clean, drain, and dry their watercraft before arriving in Yellowstone, these inspectors provide a vital line of defense against aquatic invasive species. All watercraft, including angler float tubes and paddle boards, must pass a Yellowstone AIS inspection to receive a permit prior to launching.

Banned Watercraft & Equipment

  • Watercraft with evidence of dead or live quagga or zebra mussels.
  • Watercraft previously fouled with mussels, regardless of cleaning or dry time.
  • Watercraft equipped with sealed internal ballast tanks.
  • Felt-soled footwear.

30-Day Dry Time Requirements

  • A 30-day dry time is required for all sailboats and certain complex motorized boats (inboard, inboard/outboard, or inboard jet drives).
  • Sailboats and complex motorized boats without a valid AIS inspection receipt and an intact seal demonstrating a 30-day dry time will be denied launch.
  • In addition to Yellowstone National Park seals, the park also honors inspection receipts and seals from these agencies:
  • Upon exiting Yellowstone waters, boaters can receive an exit inspection and Yellowstone seal. Returning watercraft with an intact Yellowstone seal and inspection receipt can relaunch without an additional 30-day dry time.
eDNA testing in a lab
Extracting total DNA from environmental DNA water filter samples collected in the field.

NPS / Jacob W. Frank

Monitoring & Early Detection

Yellowstone biologists monitor the distribution of known AIS populations and screen for new populations or introductions. Monitoring efforts are focused on quagga and zebra mussels in waters open to boating or with high recreational use. Early detection of AIS is key to limiting the spread and preventing introduction into additional waterways. Park researchers utilize several techniques to monitor for AIS, including environmental DNA sampling, plankton sampling for veligers (the microscopic juvenile stage of mussels), and visual surveys for invasive plants and invertebrates.

Report Sightings

If you think you’ve found a new AIS in Yellowstone, note its location, take a photo, and contact us immediately.
Several mussels with dark stripes on a beige shell sit next to a dime. They are much smaller than the dime.
Zebra mussels removed during an inspection from a boat that was attempting to launch in Yellowstone waters.

NPS / Jacob W. Frank

Incoming Threats

The greatest threat to Yellowstone’s aquatic resources is from zebra and quagga mussels. Yellowstone, Wyoming, and Montana are currently mussel-free. To reduce the risk of spreading AIS, Wyoming and Montana have increased staff and inspection stations. Biologists from Yellowstone, Wyoming, and Montana will continue to monitor aquatic resources and may implement additional preventative measures.

If nonnative mussels are detected in the Greater Yellowstone Ecosystem or surrounding area, park managers will consider a temporary closure of all park waters to all watercraft.

If nonnative mussel larvae or adults are found in Yellowstone, all park waters would close to all watercraft (except authorized boats) to prevent the spread to other waterways. The park is currently developing an AIS rapid response plan.
  • In 2023, invasive quagga mussels were found in the Snake River near Twin Falls, Idaho. In response, the state of Wyoming designated the entire reach of the Snake River from American Falls Reservoir downstream to CJ Strike Reservoir as a high-risk waterbody. As a result, a motor flush is now required for any motorized watercraft launched within this stretch of water in the last 30 days (a protocol that Yellowstone also adheres to).
  • In 2022 and 2023, adult zebra mussels were confirmed in new areas in South Dakota. One area was Pactola Reservoir in the Black Hills. The reservoir provides water for Rapid City, South Dakota, 13 miles to the east. This rules out draining the reservoir to control the mussels. The mussels are now just 27 miles from the Wyoming border. This prompted the state of Wyoming to close two nearby waterbodies to boating. Both Pactola Reservoir in South Dakota and the Snake River at Twin Falls, Idaho, are within a day’s drive of Yellowstone.

Questions & Answers


Nonnative species are ones that do not occur naturally in an area. Exotic refers to nonnatives that come from another continent. Invasive species are either nonnatives or exotics that can cause harm to an ecosystem.

“Aquatic hitchhiker” is another term for aquatic invasive species. The term was coined because of the most common way AIS are spread—riding on a boat from one body of water to another.

DNA, short for deoxyribonucleic acid, is the hereditary material in organisms that contains the biological instructions for building and maintaining them. Environmental DNA (eDNA) is nuclear or mitochondrial DNA that is released from an organism into the environment. Sources of eDNA include secreted feces, mucous, and gametes; shed skin and hair; and carcasses. eDNA can be detected in cellular or extracellular (dissolved DNA) form.

Yellowstone AIS staff currently conduct decontaminations (when necessary) at the Grant Ranger Station and Bridge Bay Marina to safeguard Yellowstone waters.

Yes. In 2023, Yellowstone staff inspected 3,093 watercraft. Among these, there were 16 decontaminations, 11 craft with foreign material physically removed, and denial of launch to one mussel-fouled boat. Since 2015, staff have inspected over 33,000 watercraft and performed more than 700 decontaminations.

Research has been conducted to study how long adult and juvenile dreissenid mussels can survive out of water, and they have not been shown capable of surviving for longer than 30 days. As a result, a 30-day dry time is considered a sufficient dry time to kill dreissenid mussels regardless of ambient temperature, humidity, and other factors.

Yellowstone will only honor seals/receipts from Idaho, Wyoming, Montana, Utah, and Colorado because watercraft inspection and decontamination protocols in these states align closely with the park’s protocol.

Watercraft (motorized or non-motorized) previously fouled by mussels, regardless of dry time, will be denied launch. Even if a boat has been decontaminated, traces of DNA can still be detected using eDNA monitoring technology. Repeated positive eDNA results could impede and confound monitoring efforts. By banning watercraft with a known history of mussel-fouling, the chances of repeated positive eDNA detections can be greatly reduced.

You will need to bring your boat to Yellowstone or one of the nearby states whose inspections/seals Yellowstone honors at least 30 days in advance of your planned launch date so that your boat can be inspected and sealed.

More Information

Zebra mussels next to a dime
Aquatic Invasive Species Ecology

At least eight AIS already exist in Yellowstone's waters.

Range with a net full of fish along a creek
History of Fish Management

Learn about the history of fish management in Yellowstone.

two park rangers inspecting the wing of a small bird
Science Publications & Reports

View science publications and reports created by Yellowstone's Center for Resources on a variety of park topics.

Canoer paddles on Yellowstone Lake

Take in the view from the water.

Angler fishing in Yellowstone during a golden morning.
Catch a Fish

Be a responsible angler and understand the regulations before you come.


Aquatic Invasive Species News

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    Last updated: May 1, 2024

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