Flathead Lake

Flathead Lake is the largest natural freshwater lake in the western United States — a vast, clear expanse roughly 28 miles long and up to 15 miles wide, cradled among the mountains of northwestern Montana between the Flathead Valley and the Mission Range, just south of Glacier National Park. Remarkably clean and clear for its size, it is a remnant of an enormous Ice Age glacial lake and a centerpiece of the region.

Ringed by forested mountains, cherry orchards, small towns and a string of state parks (including Wild Horse Island, home to bighorn sheep and wild horses), Flathead Lake offers boating, sailing, fishing, swimming and paddling across its great blue waters. The southern half lies within the Flathead Indian Reservation of the Confederated Salish and Kootenai Tribes. Famous for its summer cherries and its clear water, and set against the backdrop of the northern Rockies, Flathead Lake is a beloved recreational treasure and a natural icon of Montana.

Summer (July and August) is the prime season, when the water warms enough for swimming, the boating and sailing are at their best, the state parks and beaches are open, and the famous Flathead cherries ripen along the east shore — it is also the busiest time. Late spring and early fall offer quieter shores and beautiful light, with autumn color in the surrounding forests. The lake is lovely year-round, but the water is cold outside high summer. Summer for swimming, boating and cherries is the highlight; come midweek or early in the day for quieter beaches and launches on this popular lake.

Flathead Lake and its shores host bald eagles and ospreys fishing the water, waterfowl, loons and grebes, and along the wooded shores deer, black bears and a variety of birds, while Wild Horse Island shelters bighorn sheep, wild horses, deer and waterfowl. The lake holds lake trout, whitefish, perch and other fish (and managers work to protect the native bull and cutthroat trout). The mix of open water, islands, shore forest and the nearby National Bison Range supports rich wildlife. The lake and its parks — especially Wild Horse Island — offer fine wildlife watching and birding in a beautiful mountain setting.

Flathead Lake is large and can turn dangerous quickly — sudden winds raise big waves far from shore, so check the forecast, wear life jackets, and stay aware of changing conditions when boating or paddling. The water is cold outside high summer, and cold-water immersion is a real risk. Watch for boat traffic when swimming, and supervise children near the water. On Wild Horse Island and the shore parks, keep your distance from bighorn sheep and wildlife. Respect the lake’s size, the sudden winds and waves, the cold water and the boat traffic on this great open lake.

Flathead Lake is a premier water-recreation destination — boating, sailing, kayaking, paddleboarding, water-skiing, swimming and fishing across its vast clear waters, with a string of state parks (Wayfarers, Yellow Bay, Finley Point, West Shore, Big Arm and the boat-access Wild Horse Island) offering beaches, launches, camping and trails. Anglers pursue lake trout, whitefish and other species. Cherry orchards along the east shore draw visitors at harvest, and the lake is a base for exploring nearby Glacier National Park. Boating, swimming and exploring the island and shore parks are the signature draws of this great Montana lake.

Flathead Lake lies in the homeland of the Salish (Flathead), Pend d’Oreille and Kootenai peoples, and its southern half is within the Flathead Indian Reservation of the Confederated Salish and Kootenai Tribes, established in 1855. Settlers later came to farm the fertile valley and plant the cherry orchards for which the east shore is famous, and the lake became a recreational hub for the region. The Salish Kootenai Tribes have led notable conservation efforts, including the bison range nearby. Flathead Lake preserves this great clear lake, its rich Native heritage and its agricultural and recreational legacy, a treasured icon of Montana.

Flathead Lake is the remnant of an enormous body of water from the Ice Age — glacial Lake Missoula and the great valley glaciers that flowed south from the mountains carved and dammed the basin, and as the ice retreated some 12,000 years ago, the lake was left filling the broad glacial trough, held back by a terminal moraine at its southern end (near Polson). The surrounding Mission and Swan ranges and the Flathead Valley were shaped by the same glaciers. The lake is large but relatively shallow for its size. The great Ice Age glaciers and their moraine created the largest natural freshwater lake in the West.

Flathead Lake is renowned for its clean, clear water — one of the cleanest large lakes in the populated world — a cold, relatively nutrient-poor lake whose clarity reflects its largely forested, protected watershed draining from Glacier and the surrounding ranges. The lake, its shores, the islands and the inflowing Flathead River support aquatic life, native and introduced fish, and shoreline and island habitats. Protecting the lake’s water quality (including controlling nutrients and aquatic invasive species, a serious threat) and its watershed sustains both the ecology and the remarkable clarity and beauty of this great Montana lake.

Flathead Lake, the largest natural freshwater lake in the West, holds a treasured place among the icons of Montana — a beloved summer playground of clear blue water, sailboats and cherry orchards set against the northern Rockies, and a place of deep significance to the Salish, Pend d’Oreille and Kootenai peoples whose reservation embraces its southern half. Its famous cherries, its sparkling water and its proximity to Glacier National Park enrich its meaning. Flathead Lake is a cherished icon of Montana and the heart of the Flathead Valley.

Flathead Lake is in northwestern Montana, south of Kalispell (and its airport) and north of Missoula, ringed by U.S. 93 on the west shore and Montana 35 on the east, with the towns of Polson at the south end and Bigfork at the northeast. The string of Flathead Lake State Park units (Wayfarers, Yellow Bay, Finley Point, West Shore, Big Arm) offer launches, beaches and camping; Wild Horse Island is reached only by boat. The southern half lies within the Flathead Reservation (a tribal recreation permit may be needed for some uses). Check Montana State Parks and tribal rules for fees, access and conditions before visiting.

Montana State Parks, the Confederated Salish and Kootenai Tribes, and watershed groups work to protect Flathead Lake’s famed water quality. Visitors help above all by cleaning, draining and drying all watercraft to prevent aquatic invasive species (mussels and others, a grave threat to the lake) — mandatory inspections apply — and by preventing pollution and nutrient runoff, respecting wildlife and the islands, packing out everything, and following park and tribal rules. The lake’s remarkable clarity depends on this vigilance. Protecting the water quality and the watershed sustains both the ecology and the sparkling beauty of this great Montana lake.

All watercraft must pass a mandatory inspection and be cleaned, drained and dried to prevent aquatic invasive species — this is strictly enforced. State park fees apply at the lake units; camp only in designated campgrounds (reservations recommended). The southern half of the lake lies within the Flathead Reservation, where a tribal recreation/conservation permit may be required for fishing, boating or shore use — check tribal rules. Keep your distance from wildlife on Wild Horse Island. Pets must be leashed in parks. Pack out all trash. Check Montana State Parks and the Salish Kootenai Tribes for inspections, permits, fees and current rules before visiting.

The towns of Polson, Bigfork, Lakeside and Somers ring the lake, with Kalispell and Whitefish to the north, Missoula to the south, the Mission Mountains and the National Bison Range to the southeast, and Glacier National Park a short drive north. The Flathead Valley and the northern Rockies define the region. Flathead Lake is the sparkling heart of the Flathead Valley, a centerpiece of a Montana adventure of water, mountains and orchards, easily combined with Glacier National Park, Whitefish and the Mission Mountains.

Come in July or August for warm water, sailing and the famous Flathead cherries along the east shore — and explore the string of state parks, especially boat-access Wild Horse Island for bighorn sheep and wild horses. Launch early or midweek to beat crowds, and clean, drain and dry your boat (inspections are mandatory) to help protect the lake’s famed clarity. Watch the wind on the big open water, wear life jackets, and check tribal permit rules for the southern half. Use the lake as a base for Glacier National Park just to the north.