Montana Non-Resident Boating: AIS Pass, 90-Day Rules & Inspection Guide (2026)

Non-Resident Boating in Montana: What You Need to Know

Montana welcomes non-resident boaters to its world-class lakes and reservoirs — from Flathead Lake (the largest natural freshwater lake west of the Mississippi) to Fort Peck Reservoir and Canyon Ferry Lake. However, Montana has one of the most rigorous Aquatic Invasive Species (AIS) prevention programs in the country, and non-residents must comply with specific requirements before launching.

The two pillars of non-resident boating in Montana are: (1) the 90-day temporary use exemption that lets you operate with your home-state registration, and (2) the mandatory Vessel AIS Prevention Pass that every non-resident watercraft must carry. Both are strictly enforced by FWP wardens at boat ramps, inspection stations, and on the water.

This guide covers everything a non-resident needs to know: the AIS Prevention Pass, mandatory inspection stations, the 90-day rule, registration requirements for extended stays, and how Montana's system compares to neighboring states. For a full overview of Montana boat registration requirements, see our dedicated state page.

The 90-Day Temporary Use Exemption

Non-residents who hold a valid boat registration from their home state may operate their vessel on Montana public waters for up to 90 consecutive days without obtaining Montana registration. This exemption covers all vessel types — motorboats, sailboats, personal watercraft, and non-motorized boats.

Key rules for the 90-day exemption:

Consecutive days, not cumulative: The 90-day clock runs continuously from the date you first launch in Montana. It does not reset if you leave and return. If you leave Montana for more than 90 days and return later in the same season, a new 90-day period begins.

Valid home-state registration required: Your vessel must display current, valid registration numbers and decals from your home state. Expired registration voids the exemption.

AIS Prevention Pass still required: The 90-day exemption only waives the Montana registration requirement — it does not waive the AIS Prevention Pass. Every non-resident watercraft must carry a valid AIS Prevention Pass before launching.

Display home-state numbers: Continue displaying your home-state registration numbers on the bow. You do not need Montana MT numbers during the exemption period.

If you plan to keep your boat in Montana for more than 90 consecutive days — for example, at a seasonal marina on Flathead Lake — you must obtain full Montana registration through the County Treasurer's Office. For details on titling, see our Montana boat title transfer guide.

The AIS Prevention Pass: Montana's Unique Requirement

Montana's Vessel AIS Prevention Pass (AISPP) is a mandatory purchase for all non-resident watercraft entering Montana waters. This is Montana's primary funding mechanism for its watercraft inspection and decontamination program, which protects the state's pristine lakes from zebra mussels, quagga mussels, and other invasive species.

Where to purchase: The AISPP can be purchased online through the FWP online licensing portal, at FWP regional offices, or at authorized License Ambassador locations across the state. You can also purchase at some sporting goods stores and marinas.

Proof of purchase: No physical decal is issued. You must carry proof of purchase — either an electronic receipt on your mobile phone or a printed paper receipt — on your person or within the vessel while operating on Montana waters. FWP officers can ask for proof at any time.

Not transferable: The AISPP is tied to a specific vessel and cannot be transferred to a different boat. If you bring two boats to Montana, you need two passes.

Mandatory Watercraft Inspections

Montana operates one of the most extensive watercraft inspection programs in the western United States. All boaters — residents and non-residents — must stop at every open watercraft inspection station they encounter while transporting a boat on Montana roads.

The following flowchart shows what to expect at a Montana inspection station:

Inspection stations operate seasonally, typically from early March through late October, with more than 17 stations across the state. Major stations are located near highway borders and popular water bodies. Inspections are free of charge and typically take 5 to 15 minutes for a clean boat.

Special rules for ballast tanks: If your boat has ballast tanks or bladder systems (common on wakeboard/wakesurf boats), it must undergo decontamination before launching — even if no contamination is found during visual inspection. This is because ballast tanks are impossible to fully drain and inspect visually, making them high-risk carriers for invasive species larvae.

Columbia River Basin and Flathead Basin: Stricter Rules

Montana has enhanced inspection requirements for boats entering the Columbia River Basin (western Montana) and the Flathead Basin (including Flathead Lake, Whitefish Lake, and the Swan River chain). These areas are considered the highest-priority zones for AIS prevention because they are currently free of zebra and quagga mussels.

If you are trailering a boat into these basins — particularly from states east of the Continental Divide — you will likely encounter mandatory inspection stations on highways. Boats crossing the Continental Divide within Montana must also undergo inspection if they are entering the Columbia or Flathead Basin.

Key destinations in these protected basins include: Flathead Lake (largest natural freshwater lake west of the Mississippi), Whitefish Lake (popular resort destination), Hungry Horse Reservoir, and Swan Lake. Plan for inspection stops when heading to any of these locations.

Boater Education for Non-Residents

Montana's boater education requirements are relatively lenient compared to many states. Here is what non-residents need to know:

Non-residents who hold a valid NASBLA-approved boating safety certificate from their home state are exempt from Montana's education requirements. Montana accepts certificates from all 50 states, provided the issuing state's course meets NASBLA standards. For more on education requirements, see our guide on boater education requirements by state.

Montana vs. Neighboring States: Non-Resident Rules Comparison

If you are boating in the Northern Rockies or Northern Plains region, you may cross between Montana and its neighboring states. Here is how non-resident rules compare:

Important note for multi-state boaters: inspections performed at Idaho and Wyoming stations can fulfill Montana's pre-launch inspection requirement — but you must still stop at any open Montana inspection station you encounter while transporting your boat. The inspectors will verify your prior inspection status and may conduct a re-inspection if needed. For full details on each state, visit our Idaho, Wyoming, North Dakota, and South Dakota registration pages.

Popular Montana Boating Destinations for Visitors

Montana offers some of the most scenic boating waters in North America. Here are the top destinations for non-resident boaters:

Flathead Lake: The largest natural freshwater lake west of the Mississippi at 191 square miles. Located near Glacier National Park, Flathead Lake is famous for its crystal-clear water (visibility up to 37 feet) and spectacular mountain scenery. Multiple public boat ramps, marinas, and campgrounds surround the lake. Flathead Lake is within the protected Flathead Basin, so enhanced AIS inspections apply.

Fort Peck Reservoir: The largest body of water in Montana by total surface area (approximately 245,000 acres). Located in northeastern Montana on the Missouri River, Fort Peck offers excellent walleye, northern pike, and lake trout fishing. The reservoir has over 1,500 miles of shoreline and numerous public access points.

Canyon Ferry Lake: One of Montana's most popular recreation lakes, located near Helena. The 35-mile-long reservoir on the Missouri River is a top destination for boating, water skiing, and fishing. Multiple public ramps and campgrounds line both shores.

Glacier National Park waters: Several lakes within Glacier National Park (including Lake McDonald, St. Mary Lake, and Bowman Lake) allow motorized boating. However, motor size restrictions vary by lake — some limit motors to 10 HP or less, and others prohibit motorized boats entirely. Check specific lake regulations before trailering your boat into the park.

For more on Montana's tax advantages when purchasing a boat for these waters, see our guide on Montana boat sales tax.

Common Mistakes Non-Residents Make

Based on common enforcement issues reported by FWP wardens, these are the most frequent mistakes by non-resident boaters:

1. Not purchasing an AIS Prevention Pass: This is the number-one violation among non-residents. The pass is required before launching — not after. Purchasing after a citation does not reverse the fine.

2. Driving past open inspection stations: Bypassing an open inspection station is a violation with fines up to $1,000+. Watch for signs on major highways and always stop when directed.

3. Not draining ballast tanks: If your wakeboat has ballast tanks, they must be fully drained before arriving at a Montana inspection station. Boats with undrained ballast will be required to undergo decontamination, which can add hours to your trip.

4. Assuming home-state inspection counts: While Idaho and Wyoming inspections are recognized, inspections from other states generally are not. If you're coming from Minnesota, Wisconsin, or any Great Lakes state, you will need a Montana inspection.

5. Operating with expired home-state registration: The 90-day exemption requires valid home-state registration. An expired registration means you are operating an unregistered vessel in Montana — a citable offense.

6. Not carrying proof of AIS Pass: FWP officers can request proof of your AIS Prevention Pass on the water. Keep the receipt (digital or printed) accessible at all times while boating.