If mussels are detected on a boat that officials cannot ensure decontamination, the rule would allow impoundment or locking the boat to the trailer until it fully dries, Boos said.

“This rule for dry time is intended for worst-case scenarios,” he said.

Those worst-case scenarios are rare, Boos emphasized. Similar rules in Idaho have only impounded a handful of boats since 2009. Of the five boats found with mussels at Montana’s aquatic invasive species checkpoints last year, none would have required either impoundment or locking, he said.

FWP does not want to impound boats, which includes assuming liability, and tries to work with owners to make the decontamination processes as easy as possible, he said.

An additional rule would require owners while transporting boats to remove drain plugs, valves or any other device that prevents water from draining, with the exception of regulations allowing transport of live bait. When leaving a waterbody, all aquatic vegetation would need to be removed at the boat ramp or parking lot from boats, trailers and equipment.

Several boaters grilled FWP on the rules and risk assessments for boats, challenging the practicality and potential overreach while maintaining a desire to stop invasive transport.