Yellowstone boaters warned to clean gear before May 23 launch

MAMMOTH HOT SPRINGS, Wyo. — Yellowstone National Park (YNP) reminds boaters and anglers to clean, drain and dry their boats, trailers and gear before entering park waters as the 2026 boating season starts May 23 and runs through Oct. 31.

Park officials said in a release that Yellowstone faced a growing threat from zebra and quagga mussels after recent detections in waters within a day’s drive of the park, including the upper Colorado River in 2025, Pactola Reservoir in 2022 and the Snake River in 2023.

YNP asks visitors to remove plants, animals, mud, sand and other debris from boats, anchors, boots and equipment. People are also urged to drain all water before arrival, leave drain plugs out during transport and dry compartments and gear completely in the sun.

Felt-soled footwear remained banned because it can carry microscopic disease organisms even after cleaning.

Yellowstone also requires a 30-day dry time before launch for sailboats and some motorized boats, including inboard, inboard/outboard and inboard jet vessels. The park said nonmotorized watercraft and boats with outboard motors were exempt.

Larger trailered boats posed the highest risk because they were harder to inspect and less likely to be fully drained, dried or decontaminated. The park added that hot-water decontamination did not always remove every mussel.

Yellowstone said any watercraft previously fouled by mussels would be denied launch regardless of dry time. Officials warned that launching those boats could trigger false mussel detections in routine environmental DNA monitoring and disrupt park operations and recreation.