Big Arm State Park in Montana, USA - map and visitor information

Research checked: 2026-10-27. Check linked official notices before travel.

Big Arm is the west-shore unit of Flathead Lake State Park in Montana, managed by Montana Fish, Wildlife & Parks. Its pebble beach, pine-and-juniper campground and mountain views make it a practical base for a lake visit. Plan around the campground and water-service seasons before choosing an overnight stay.

A lakeshore base with mountain views

The shoreline looks toward the Swan and Mission ranges and Wild Horse Island. A short visit can center on the beach and picnic areas; a longer stay adds hiking and boating without changing bases.

Know before you go

Fees, hours, and seasonal access

Food storage and lake conditions

Store food and other attractants in a closed hard-sided container or vehicle whenever they are not in immediate use, day or night. Tent campers without vehicles may use the food lockers. Use the bear-resistant dumpsters, and never burn waste in a fire ring. Check wind and wave conditions before going onto the lake.

Respect park and tribal rules

The park lies within the Flathead Reservation. Recreation on tribal land outside the park requires a tribal recreation permit and compliance with tribal rules. Fishing on the southern half of Flathead Lake or other reservation waters requires a tribal fishing license. Keep pets on a leash no longer than 8 feet unless posted otherwise, and keep them off swimming beaches. Read the state park visitor rules before bringing a pet.

Camping reservations

Use the Montana State Parks booking service or call 855-922-6768 to select a campsite or yurt. The state campsite reservation season runs from the third Friday in May through the third Sunday in September, within a longer park campground operating season. Confirm arrangements directly for stays outside that reservation period.

Location and road access

The entrance is at 28031 Big Arm State Park Road, Big Arm. The unit is 15 miles north of Polson along U.S. 93 on the west side of Flathead Lake. Use the unit-specific park map when choosing a campsite or locating the shoreline facilities.

Nearby parks

West Shore Unit, Flathead Lake State Park, is farther north along the same U.S. 93 corridor, south of Lakeside; its day-use area is open daily. Finley Point Unit, Flathead Lake State Park, is on the southeast shore north of Polson, so reach it by road around the lake rather than treating the water crossing as a road shortcut. Its park season is April–October.

Choose a shore visit or a day on the water

Hike for mountain views, picnic beside Big Arm Bay or spend time on the pebble beach. Boating, paddling, swimming and fishing are offered here. Keep the tribal fishing-license boundary and weather-dependent dock availability in mind when planning a water outing.

Camping and seasonal services

The campground has 41 campsites, including one wheelchair-accessible site, plus a group campsite and three yurts. The maximum RV or trailer length is 40 feet. Bear-resistant lockers support tent camping; water, showers and flush toilets follow the shorter service season shown above. Ask staff about the specific site and route if you need accessible facilities.

About the Big Arm unit

Big Arm is one unit of Flathead Lake State Park, within the Flathead Reservation. That relationship matters when a visit extends beyond the park boundary: a park visit does not replace the required tribal permits for other reservation lands or waters.

Woodland and shoreline habitats

Mature ponderosa pine and juniper shade the campground. Bird-watching and wildlife viewing are park activities; secure food and give animals space while exploring the shoreline and trails.

Contact

Use the official Big Arm park page for the park map and current notices. The year-round Flathead Lake ranger station number is 406-837-3041; email [email protected].