Big Arm State Park

Big Arm State Park

Big Arm State Park is located on the western shore of Flathead Lake and less than 20 minutes outside of Polson, MT.

Flathead is the largest natural freshwater lake in the western United States. Twenty-eight miles long and 15 miles wide, Flathead Lake is renowned for its beauty.


Big Arm State Park

Download Campsite Map


Download Park Map

Looking to camp?

The park has both flush and vault toilets, tent/RV sites, bear-resistant storage lockers, boat trailer parking, sheltered picnic tables, drinking water, grills/fire rings, firewood, picnic tables, trash cans, and coin-operated showers. RV/trailer size is limited to 30 feet in the 41 site campground. 

There are also seven tent-only campsites available. Big Arm has also added two yurts, including one that is entirely ADA accessible. Plans for more yurts, cabins and other accommodations are in the works. 

You will need a joint state/tribal for fishing license or fishing at this park, and campers may stay only 14 days during a 30-day period. Pets are required to be on leashes. Fees are charged for day use and camping.

  • Lounge on the long pebble beach or take a dip in the lake to cool off.
  • Come prepared with your joint state/tribal fishing license if you want to try and catch a big one!
  • Take a scenic hike on the trail, which provides outstanding views of the mountains.
  • Catch a glimpse of wildlife, including birds, deer, and even a bear from time to time
  • Spend a day on the lake boating, skiing or wakeboarding
  • Experience a feeling of tranquility while camping under a collection of mature ponderosa pine and juniper trees
  • Plus so many more!
  • Open April through October
  • Day-Use Area Open Year-Round
  • 217 acres
  • ADA Accessible 
  • Pets Allowed
  • Toilets (Vault & Flush)
  • Water
  • Yurt 
  • Firewood for Sale 
  • Picnic Shelter
  • Boat Launch

On Flathead Lake's Big Arm Bay, this park is a popular destination for camping, swimming, fishing, picnicking, and as a jump-off point to Wild Horse Island.

Big Arm's pebble beach is a popular place to get your feet wet or take a swim in the lake.

Mature pine and fir trees surround the campsites at the park. Other activities at the park include fishing for lake trout, boating, fishing, swimming, camping, picnicking, bicycling, hiking the park trails, wildlife viewing, scuba diving, and water-skiing.

The water in Ackley Lake comes from the Judith River and is stockpiled for irrigation use!

Did You Know

Curious what other visitors have had to say about the park?

"Wonderful camp grounds. Nice hosts, clean restrooms - overall well run and managed. It's a fantastic place to camp and play on the lake."

"Camped here with our boat. It was perfect! Great roomy sites and lots of shade. Yurt was very clean and bathrooms were better than most campsites we've been too."

"Big Arm campsite is super nice for fishing and swimming. Would 100% recommend it!"

"Beautiful place. Clear lake. Friendly people"


Quick Facts
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    Day use area open year-round

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    Open April through October

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    Available mid-May through mid-September

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    Shower House & Flush Toilets

    Open mid-May through mid-September

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    Normally available mid-March through November, weather permitting. 

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    28031 Big Arm State Park Road

    Big Arm, MT 59910

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