Maryland officials have signed a legal agreement with the Columbia Country Club promising to shift the Purple Line’s proposed course to better protect the club’s Chevy Chase golf course — one of several concessions setting the country club apart from hundreds of other property owners along the route.

The country club, long viewed as one of the most well-financed and politically connected Purple Line foes, said that in exchange it would drop all opposition, according to the agreement reached June 20 by the club, the Maryland Transit Administration and Montgomery County. That includes refraining from filing or funding any lawsuits, which could significantly delay construction.

Those who signed the 25-page agreement, which The Washington Post obtained under Maryland’s public records law, are legally prohibited from discussing it publicly.

The 16-mile Purple Line, which would run between Bethesda in Montgomery County and New Carrollton in Prince George’s County, is designed to provide faster and more-reliable east-west transit than buses and connect Maryland’s spokes of the Metrorail system with neighborhoods, MARC commuter rail stations and Amtrak stations.

The light-rail line does not have full construction funding, but state officials are preparing to seek private investors as they compete for federal aid. If construction begins in 2015, the line could open in 2020.

The country club’s opposition to an east-west transitway dates back decades as plans have long called for trolleys or trains to bisect the golf course west of Connecticut Avenue and north of East-West Highway. Trains would run along what is now the wooded Georgetown Branch running and biking trail, which crosses the golf course separated by a chain-link fence and mature trees. Under current plans, two-car Purple Line trains would run through the golf course 70 times a day.

Moving the proposed light-rail line about 12 feet to the north for 1,700 feet through the club’s 100-year-old golf course would help protect clubhouse views and spare four holes, according to the agreement and state documents. Other concessions include a one-year limit for construction vehicles to use club property, guaranteed four-foot sound walls and promises of meetings at least every three months to discuss ongoing work.

The county also agreed to give the club, at no cost, “exclusive” use of two golf-cart underpasses and county-owned land where the golf course already exists.

Elsewhere along the route, state officials plan to use eminent domain to condemn 116 homes and businesses and buy pieces of front and back yards needed for the project. Any negotiations probably would center on the lost property’s fair market value, not the state’s legal right to acquire it. The state would not need to condemn country club property, because the county already has a right of way about 100 feet wide through the golf course.

The state also has the right to lease private land during construction with no legal guarantee of how long that work will take.

Community concerns have prompted other changes to the Purple Line’s design, state officials have said, including a smaller train storage yard farther from homes in the Lyttonsville community of Silver Spring and improved pedestrian and bicycle access.

But other private property owners do not have legally binding agreements or guarantees of regular meetings with state transit officials, like those granted to the country club.

Map of the proposed Purple Line

Phil MacWilliams, president of the Coquelin Run Citizens Association, said the 40 or so residents whose homes abut the Purple Line alignment east of Connecticut Avenue would love to have the state’s assurances of sound walls in a legally binding document.

“I think it’s great the country club can secure these concessions and promises, but what about the rest of us without the same clout or resources?” MacWilliams said.

The document states that the people who signed it, including the state’s top two Purple Line planners and Montgomery’s director of transportation, will “confine all future public statements” about the agreement to this: “The Columbia Country Club, Maryland Transit Administration and Montgomery County have entered into an agreement that resolves various issues relating to the planning, design and construction of the Purple Line and Capital Crescent Trail Project.’”

Maryland transportation officials declined to say even that much. “The agreement speaks for itself,” MTA spokeswoman Erin Henson wrote in an e-mail.

She later added that the MTA works with “a range of property owners” while planning transit projects. “We work to make reasonable accommodations and rely on property owner input to determine if there are ways to balance everyone’s goals,” Henson wrote. The agreement, she said, “reflects a consensus view that we need to move toward solutions and not default to hard and fast positions.”

Henson said the state is “in discussions” with other property owners, but this is the only legal agreement. The changes through the golf course do not add any costs to the project’s $2.2 billion budget, she said.

Montgomery County officials declined to comment.

“The agreement speaks for itself,” county spokesman Patrick Lacefield wrote in an e-mail.

Montgomery County Council member Roger Berliner (D-Potomac-Bethesda), who chairs the council’s transportation committee and whose district includes the country club, said he did not know about the agreement until The Post contacted him Wednesday.

He said he had not had a chance to read it but said, “Presumably, it’s in the public interest.”

“The country club has historically been a vigorous opponent of the Purple Line,” Berliner said. “Litigation could have tied this project up.”

Ben Ross, a longtime Purple Line advocate, agreed. “The country club has always been the main obstacle to building a Purple Line,” Ross said. “To get this out of the way, it’s extremely well worth it.”

As part of the agreement, the club promised not to criticize or demonstrate against a transit line. Columbia Country Club President Geoff Gonella, who signed the document, said Wednesday that he could say only that the agreement “resolves various issues.”

He said the club has had lawyers and consultants review Purple Line plans but said no decision had been made about possible legal action before the agreement was signed.

In a June 24 letter to members, obtained by The Post, Gonella wrote that the agreement “provides several important concessions to the club” that would preserve part of the golf course south of a Purple Line alignment.

“We will have to relocate the 14th green and may have to reorient the 2nd fairway,” the letter said. “We have had our golf course architect review the changes, and he is confident the modifications can be accomplished, and may even enhance the course.”

The agreement also states that the MTA will build the two golf-cart underpasses and stage construction “so that the course remains open at all times,” Gonella wrote.

Gonella’s letter notes that the club, its officers and its governors agreed to “not do anything to oppose the project going forward.” It added that “members remain free to oppose the project in their individual capacities or as part of other groups and in any manner they see fit.”

Montgomery County bought the trail land in 1988 from the B&O Railroad as part of plans for a future trolley line between Bethesda and Silver Spring. The golf course was designed around the railroad, which opened in 1909, according to a state Purple Line study. The club opened at its current location in 1911, according to its Web site.

CORRECTION: An earlier version of this story mistakenly stated that the Purple Line has no construction funding. This version has been corrected.