Stopping the Spread

boat inspection, watercraft, invasive species

A look at Montana's invasive species.

A whopping 174,000—that’s how many watercraft inspections Montana Fish, Wildlife & Parks, along with its partners, conducted last year. They found 35 vessels fouled with mussels and 1,100 vessels transporting aquatic weeds. For some contrast, the year before, they intercepted only 170 vessels transporting aquatic weeds. A massive influx of tourists coming to Montana last summer tested FWP’s inspection sites, and while the department gathered plenty of helpful data, it’s essential to do our part in keeping Montana’s waters pristine and safe.

Aquatic invasive species (AIS)—namely, mussels—are one of the primary threats to southwest Montana waters. Though Montana does have naturally-occurring mussels, the invasives are much smaller than their native counterparts. Invasive mussels can unfavorably rattle fish populations, reduce water quality, outcompete native species, and pose a major threat to irrigation systems. We’ve seen the detrimental effects they’ve had in the Midwest and Southwest; now they’re trying to make their mark on Montana.

Though the biggest threats come from out of state, significant risk exists within our state’s boundaries. Many native species east of the Continental Divide would wreak havoc on the waters west of the divide. Regardless of location, we all need to remember to clean, drain, and dry our watercraft, and practice the same principles with our waders and any other gear that has prolonged contact with the water.

To clean your watercraft to spec, remove any large pieces of plant matter, mud, and water at the takeout. Once you make it home, wash your boat thoroughly, drain it completely, and make sure it has time to fully dry before your next launch. You can do this with a high-pressure rinse from a car wash, or at home with your garden hose. It’s not rocket science, but it is important. Whatever the gear or equipment is, if it touches wild water, it gets drained, washed, and cleaned. FWP has chosen to focus its efforts on watercraft, because they are the most common carriers of AIS; but there are plenty of other ways to bring unwanted species into Montana waters.

Keep in mind that if you’re visiting Montana, you need to buy a Vessel AIS Prevention Pass before hitting the water. They are relatively low-cost at $30 for motorized watercraft and $10 for non-motorized watercraft. If you’re transporting watercraft into Montana—even if you live here—you are required to have your vessel inspected prior to launching and must stop at all open watercraft-inspection sites that you encounter.

Help us all continue to enjoy southwest Montana by making sure you do your part to keep our waters free of invasive species. For more information, visit