GOLDENDALE, Wash. — The big winds that rake this nearly treeless channel of the Columbia River Gorge lightened somewhat last weekend.

“It was calmer than usual,” said Colleen Schafroth, the executive director of the Maryhill Museum of Art, high on a bluff above the Columbia. “But the turbines were definitely turning.” And after last weekend, when Maryhill celebrated the opening of a $10 million addition, when benefactors strolled the new plaza that offers views of the river, Mount Hood and the wheat fields across the river in Oregon, and when guests dined outside the little cafe, everyone will know better than to complain when the wind picks up again.

After all, in addition to a sculpture garden featuring artists of the Pacific Northwest, Maryhill’s grounds — all 5,300 acres of them — now include 15 wind turbines, part of a vast installation that sends 500 megawatts of electricity to Los Angeles and about $250,000 each year into the operating revenues of one of the most isolated art museums in the contiguous United States.

Maryhill raised the money for the addition through public and private grants — no small feat given its size and location and the challenges facing arts institutions — but museum officials say revenue from leasing its land for wind energy provided the confidence and financial security to proceed with the capital campaign at a time when the number of visitors — about 45,000 a year — is well below its peak in the 1990s.

“Essentially, it’s an endowment,” said Jim Foster, the past president of the Maryhill board. “It really gave us the freedom to go forward.”

The terms of the lease will last for 20 years, with the potential for a 20-year extension. The revenues will make up nearly a fifth of Maryhill’s $1.3 million annual budget. Those who put together the arrangement say they know of no other like it.

“We’ve never had a situation even close to this,” said Gary Hardke, the president of Cannon Power Group, the California company that leases the land from Maryhill and operates the wind farm, called Windy Flats. “It really put a floor under their annual revenues.”

Maryhill has never been conventional. It opened in 1940 after its founder, Sam Hill, had given up on his original dream. Hill, a builder of roads and railroads (as well as the Peace Arch on the Canadian border in Blaine, Wash., and a replica of Stonehenge near Maryhill), had planned to establish a Quaker farming community there, but he could convince no Quakers to come. Soon he gave up on living in the area, choosing to remain at his home in Seattle.

Yet his mansion, made from poured concrete, was not going anywhere. Artistic friends, led by the modern dancer Loie Fuller, persuaded Hill to turn it into a museum, one whose eclectic combination of exhibits — chess sets, Rodin sculptures, American Indian artifacts, a room with religious icons, a re-creation of Theatre de la Mode, British paintings — sometimes feels as unlikely as the museum itself.

The addition increases the gallery space, but most of the new square footage is devoted to providing Maryhill with things larger museums take for granted: a dedicated collections room, space for educational and other programs, and a discrete cafe with views of the gorge. (The old one flowed directly into the Rodin exhibits.) Some regulars have expressed disappointment.

“I thought they’d get a lot more paintings out of the attic,” said Diane Born, who visited the addition with her husband, Fred, last week.

Schafroth said she understood those complaints, but that Maryhill needed to strengthen its position as a destination for rural school groups and others who sometimes drive three or four hours to visit, and that it also needed to improve the experience in the existing galleries.

“It was really awkward for people who loved art,” she said of the old cafe. “You’d hear the espresso machine.”

Capturing the wind is not the only way Maryhill uses its land to benefit its bottom line. The museum brings in about $60,000 by leasing acreage for fruit orchards and vineyards. It earns about $20,000 each year by renting access to the Loops Road, a series of curving roads built by Hill that is now the site of the annual Maryhill Festival of Speed, a skateboarding contest.

The museum is in Klickitat County, which has just 20,000 people. Portland, the nearest big city, is two hours away. Even Goldendale, with fewer than 4,000 people, is more than 10 miles away.

“To call Maryhill Museum a pretty remote place is a bit of an understatement,” said Foster, a lawyer in The Dalles, who grew up in the gorge and recalled playing on the museum grounds in the 1950s.

Schafroth, who started at the museum in 1986 as its education director, noted that gas prices were going up, a challenge for a museum so far from population centers, and that the young people Maryhill wants to reach must be convinced that there is value in confronting real objects, not just images on screens.

“Why do people want to come here?” she said. “Every day we have to be out there making that case.”

Schafroth slapped a massive foundation wall that was left exposed as part of the renovation, marking the transition from the old building to the new one, then said of Hill, “He built this place to last forever.”