Mammoth Hot Springs, WY – Yellowstone National Park emphasizes that boaters and anglers must bring clean, dry, and drained boats after announcing its boating season at the park beginning May 28 and ending October 31. The news release says all boats must meet these criteria to prevent the spread of Aquatic Invasive Species (AIS) in the park’s waters. 

Aquatic Invasive Species can severely affect the natural ecosystem of waters in Yellowstone National Park. The most recent AIS incident happened this February when an angler caught a smallmouth bass that was not native to the Gardner and Yellowstone rivers near Gardiner, Montana. Other potential threats are invasive mussels, such as Zebra and Quagga mussels. If either type of these mussels are found in Yellowstone waters, the park may prohibit access to any watercraft vehicles in the waters to prevent the spread of the invasive species.

Boaters and anglers must make sure their boats are clean of any debris using hot, high pressured water. Boats must also be drained of water from all equipment and compartments and dried in the sun for at least five days. This must be done prior to arriving at the park. Meeting these requirements is essential to prevent AIS from spreading to other bodies of water.

AIS Inspections and Yellowstone National Park permits are also required for any tube floats used in the water and must be done before boaters and anglers are allowed on the waters.

Full Press Release from Yellowstone National Park Below:

MAMMOTH HOT SPRINGS, WY – Yellowstone National Park announces boating and fishing season will begin Saturday, May 28, and emphasizes clean, drain and dry to prevent the spread of aquatic invasive species (AIS) and protect park waters. The season will close Oct. 31.

Boaters and anglers must clean, drain and dry all boats and equipment prior to arriving in the park to minimize the risk of introducing AIS into Yellowstone’s waters. Watercraft equipped with sealed internal ballast tanks are banned from all park waters as inspections cannot always detect aquatic invaders in these types of boats. In addition, felt-soled footwear is banned because they can carry microscopic disease organisms even after cleaning.

Clean, Drain, Dry

Boaters and anglers: ensure you do not bring AIS to the park.

Clean all plants, animals, mud, sand and other debris from your boat, anchor, boots and equipment. Use high-pressure, hot (120-140F) water if possible.

Drain all water from your boat, including the motor, bilge, livewell and other compartments before you arrive. Leave drain plugs out during transport. Do not move water or organisms from one water body into another.

Dry all compartments and equipment in the sun for five days.

Clean, drain and dry requirements are critical steps to protect the park’s and nation’s waterways.


AIS pose a grave and growing threat to the Greater Yellowstone Ecosystem and surrounding economies. AIS can quickly and drastically transform habitats and food webs, causing permanent declines in sport fish and food resources for native wildlife.

Recent AIS Threat

In February 2022, an angler caught an invasive predatory smallmouth bass at the confluence of the Gardner and Yellowstone rivers just north of the park’s boundary at Gardiner, Montana. Soon afterwards, biologists sampled the Gardner River upstream of where the smallmouth bass was caught and did not find evidence of this species within Yellowstone. However, since anglers are highly effective at suppressing invasive fish in waters where they coexist with native species like cutthroat trout, the regulations now require them to kill and report any smallmouth bass if caught within park waters.

Potential Future Threats

Dreissenid Mussels, including Zebra and Quagga Mussels, are among the world’s most harmful invasive species, with large and widespread ecological and economic effects. If Zebra or Quagga mussels are found in Yellowstone, park waters may close to all watercraft to prevent the spread to other waterways. People are encouraged to report violations and potential discoveries of AIS. The park will continue efforts to develop an AIS Management Plan and Rapid Response Framework in collaboration with the surrounding states.

Permits and inspections

Watercraft and angler float tubes must have a Yellowstone National Park permit and AIS inspection prior to launching in park waters. Permits and inspections are available for purchase 8 a.m. to 4:30 p.m. seven days per week during the summer season at the following locations:

Motorized and non-motorized watercraft (including angler float tubes)

  • Bridge Bay Ranger Station
  • Grant Village Backcountry Office
  • Lewis Lake Ranger Station

Angler float tubes only

  • West Yellowstone Visitor Information Center
  • Bechler Ranger Station
  • Mammoth Hot Springs Backcountry Office
  • Northeast Entrance

Yellowstone fishing permits can be purchased at in-park stores, vendors in surrounding communities or online via

Read more about boating, fishing and AIS on the park’s website.