There are private islands, and then there is Cromwell Island. Rising out of the gin-clear water of Flathead Lake, the largest natural freshwater lake west of the Mississippi, this 348-acre island is believed to be the largest privately owned freshwater island in the western United States held under a single ownership. Nearly three miles of shoreline wrap around meadows, irrigated pasture and ponderosa forest, climbing to a summit some 500 feet above the lake at the island's centre, where the Mission Mountains hold snow most of the year on the southeastern horizon.
What lifts Cromwell beyond even that company is what stands at its heart: a stone villa of more than 45,000 square feet, modelled on a 16th-century French estate, its exterior complete and its interior left deliberately unfinished, a free-span shell waiting for one owner's imagination to finish it. Beside it, a fully finished guest villa is ready to live in from the day the sale closes. This is a legacy property in the truest sense, offered at a scale that simply does not come to market in the American West.
The Villa
Conceived in the 1990s by Robert M. Lee, founder of Hunting World, and his wife Anne, the Villa was built the slow way and built to last for centuries. The shell is cast-in-place concrete with epoxy-coated rebar, faced in Montana travertine and dolomitic limestone, roofed in Ludowici terracotta tile, and finished with mahogany windows and doors. Twin suspended staircases rise through the entrance hall, and a helical staircase climbs the north tower. Inside, the plan was drawn for three to four bedrooms and nine bathrooms, with radiant floor heat already installed throughout, but the free-span construction means the interior can be reimagined entirely: a private residence of almost any configuration, a lodge, or a members' club. Construction paused when the family's focus moved to Lake Tahoe, leaving the rarest of opportunities, a palace-scale exterior in finished stone with a blank canvas inside.
The Guest Villa and the Dock
A short walk from the Villa, the 4,700 square foot Guest Villa is complete and move-in ready, so owners and guests can enjoy the island from day one while the main house takes shape. On the water, the dock offers five slips of varying sizes, the largest built for a 65-foot yacht and believed capable of handling closer to 70 feet. Included in the sale is the island's own 1961 custom 60-foot ferry barge, the vessel that hauled the stone, concrete trucks and materials that built the estate, and a crew cab's worth of working infrastructure most island properties never achieve.
Land and Water
The island is roughly square, with its summit of about 3,400 feet above sea level almost dead centre and its shoreline at about 2,900 feet. About 40 percent of the land is forested, 46 percent is grazing land, and some 13 percent is irrigated, with the balance around the homesites. The water is the famous Flathead clarity: over the rocky shallows the lake runs a palette from neon turquoise to deep cobalt, and on calm days boats appear to float on air. Two wells serve the island, one producing 30 gallons per minute for the two villas and a second at 24 gallons per minute near the dock, alongside a permitted right to draw lake water for irrigation, lawns, recreation and stock. Mule deer are resident, and the surrounding lake is renowned for lake trout, whitefish and yellow perch.
Access and Utilities
For all its privacy, Cromwell is engineered for easy, year-round living. A mainland ferry landing with a large boat ramp gives year-round access, and the island is also reached by boat, helicopter or seaplane. Five submerged agitators keep the ferry channel free of ice through the winter. Three-phase power arrives by submerged cable; a 750 kW Caterpillar generator with three 8,000-gallon diesel tanks can carry the island for an estimated eight to twelve weeks. Between the two villas, utilities are housed remotely and distributed through underground tunnels, with 30,000 to 40,000 gallons of buried water storage, five fire vaults and an underground 100-yard shooting range among the installed infrastructure. Glacier Park International Airport near Kalispell is under an hour away, Missoula International about an hour and a half, the town of Lakeside roughly 15 miles north, and Glacier National Park and Whitefish Mountain Resort within day-trip range.
Lifestyle and Value
Days on Cromwell Island set their own rhythm: coffee on the stone terrace as the sun hits the Missions, a morning swim in water clear to the bottom, an afternoon sail, deer drifting through the meadow grass at dusk. Summers bring highs in the mid to high 80s with nights in the 50s; winters are a quieter, snow-covered version of the same privacy. At $72,000,000, with estimated taxes of about $131,075 a year and cash terms, the island is offered as what it is: a monumental piece of the American West, an unfinished palace, and a finished private world around it. Properties of this acreage, on water of this quality, under one ownership, are not merely rare. In this part of the world, this is the only one.
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