Flathead Lake in northwest Montana is the largest natural freshwater lake west of the Mississippi; slightly larger than Lake Tahoe at 27.3 mi. long, 15.5 mi. wide, and max depth of 370.7 ft.

As one of the cleanest in the world, Flathead Lake is perfect for OPEN WATER SWIMMING! No sharks, no jellyfish, and no lane lanes...just clear, clean, and crisp water!

Boettcher Park is located on the southern shore of Flathead Lake in Polson MT.

In addition to a roped off swimming area between two docks, this park is a great place for the entire family with a children's playground and a LARGE lawn area. The park offers three covered areas which can be used for Weddings, family reunions, and parties!

Unless you like your water COLD, the effective swimming season is June through September. Average water temps in June are in the 60s, 70s in July and August, and then back down again in September.

Summer air temperatures average in the mid-70s to mid-80s.

The Golf Course concession is open at the park during the summer season and serves sandwiches, drink, and soft-service ice crease!

Bathrooms are available and parking is easy.

Swim Guide shares the best information we have at the moment you ask for it. Always obey signs at the beach or advisories from official government agencies. Stay alert and check for other swimming hazards such as dangerous currents and tides. Please report your pollution concerns so Affiliates can help keep other beach-goers safe.

Beach conditions change constantly, and it is never wise to swim in open water up to 48-hours after a heavy rain. Please use caution!

The description above was copied from or heavily based on Swim Guide, with permission.

More Information

• Swim Guide - Weather and water quality for Boettcher Park - Flathead Lake and 8,000 other beaches.