YOSEMITE VALLEY — With the onset of spring, visitors are returning to see the waterfalls, granite cliffs and snow-capped peaks of Yosemite National Park. But a 14-year-old lawsuit could soon force sweeping changes and eliminate popular activities in one of America’s most beloved national parks.

In the name of restoring the park’s natural setting, a new proposal by the National Park Service would ban bicycle and horse rentals in Yosemite Valley and remove the ice rink at Curry Village. Swimming pools at the Yosemite Lodge and Ahwahnee Hotel would be torn out. Rafting rentals on the Merced River would end. The longest stone bridge in Yosemite Valley would be demolished. Even the Yosemite Art Activity Center, where families learn water colors, would go.

The changes — which will be discussed by park officials at a public meeting Thursday in San Francisco — are part of a new set of principles for the park known as the Merced River Plan. The 2,500-page document, released in January, comes after years of lawsuits over what should be allowed in Yosemite Valley and the Merced River that flows through it.

In many ways, the document is a symbol of the near-impossible mission of the National Park Service: providing public recreation while preserving spectacular landscapes.

“Some people want much less retail, much less lodging, fewer restaurants,” said Kathleen Morse, Yosemite’s planning chief. “Other people say they want those things because they are fun and part of the mix of national parks. Who’s to say what’s right? It’s in the eye of the beholder. It makes it really tough.”

The plan calls for the removal of stone Sugar Pine bridge, built in 1928 and located behind the Ahwahnee Hotel, because its abutments impede the flow of the Merced River and cause erosion. It also recommends rebuilding about 40 percent of the 406 campsites lost in a 1997 flood, restoring 203 acres of meadows and improving parking. Visitors still would be allowed to bring bikes, horses or rafts to the park. But critics say the park service has gone too far.

“You have no idea how many people have told me, ‘The reason I support this park is because when I was a little kid my parents took me camping or I went for a horseback ride or we biked around the valley,'” said Bob Hansen, former executive director of the Yosemite Fund, a nonprofit group in San Francisco.

Over 20 years, Hansen raised $92 million to restore areas around Yosemite Falls, Glacier Point and Tunnel View, as well as to fund nature programs for thousands of children.

“The park service has lost a number of court battles, and I think they are battle weary,” Hansen said. “They are being so ridiculously cautious that they have lost their view of the balance between recreation and protecting resources.”

Others say the plan is a good step to restore nature.

“Yosemite Valley is absolutely magnificent. You ought to be able to look around and enjoy it,” said John Brady, chairman of Mariposans for the Environment and Responsible Government, an environmental group.

“You don’t need a bunch of swimming pools there. You can ice-skate in lots of places. You don’t have to do it in Yosemite Valley.”

Brady, a retired Army officer, said he would support the park going even further, such as tearing down Yosemite Lodge, which is not part of the proposed plan.

“There’s only one Yosemite Valley and one Merced River,” he said. “I’m not in favor of turning Yosemite Valley into a destination resort, like Disneyland.”

The park service and big environmental groups have never advocated for ending bike rentals or the ice rink. The new proposal is the unintentional result of an attempt to protect the river three decades ago.

In the mid-1980s, a developer proposed building several hydroelectric dams on the Merced River just west of the park, in a scenic canyon along Highway 140. Environmentalists fought back. Former Republican Sen. Pete Wilson and Democrats Alan Cranston and Tony Coelho pushed a bill in Congress to designate the Merced River as a “national wild and scenic river” to block the dams. President Ronald Reagan signed it in 1987.

A decade later, a huge January flood destroyed hundreds of campsites and motel rooms in Yosemite Valley. As the park planned how to replace them, two small environmental groups, Friends of Yosemite Valley and Brady’s group, sued in 1999. They said the government was violating the National Wild and Scenic Rivers Act, because the law required it to draw up a plan for how to “protect and enhance” the river.

Doing that meant not rebuilding as many commercial features as had been there before the flood, they argued, and possibly limiting visitation. In a key 2008 ruling, the Ninth Circuit U.S. Court of Appeals said restaurants, hotels and shops, along with bicycle and horse rentals, the ice rink and other activities, contributed to the “degradation” of the river.

The park service hadn’t shown how those activities would “protect and enhance” the river, as the Wild and Scenic Rivers Act requires, the court found.

“We were trying to block the construction of dams near the park. We weren’t trying to ban recreation,” said Ron Stork, policy director of Friends of the River, a Sacramento group that fought for the river protections in the 1980s. “I’m heartbroken about this.”

Morse, the chief Yosemite planner, acknowledged that the park service’s lawyers are behind the proposal to ban the recreational activities to comply with the court — and that the activities don’t harm the river.

She said there still is a chance park planners could find a solution. For example, the park could allow bike rentals outside the quarter-mile zone the law affects on each side of the river.

The congressman whose district includes Yosemite is spitting mad.

“The park service is hanging out a ‘Tourists Go Home’ sign,” said Rep. Tom McClintock, R-Granite Bay. “The park service leadership has forgotten that they work for the American people, and Yosemite Valley belongs to the American people and the park service’s job is to welcome and accommodate them, not restrict and harass them.”

McClintock said he will introduce an amendment to the park service budget to block removing recreational activities in Yosemite Valley.

Meanwhile, on a recent sunny day, visitors were split on the park plan.

“Banning bike rentals is kind of silly,” said Luisa Haddad, of Santa Cruz. “They should be promoting alternative transportation in the valley.”

Joyce Kane, a visitor from the San Fernando Valley who was bicycling near the Ahwahnee, mulled it over.

“I might be upset at first,” she said. “But if you are coming here for the swimming pools and ice skating, you should be going somewhere else.”

Paul Rogers covers environmental issues and resources. Contact him at 408-920-5045. Follow him at Twitter.com/PaulRogersSJMN.