The plunging waterfalls and soaring crags chiseled by the Merced River draw millions of visitors each year, but the crowds are precisely what threatens the waterway and the park.
Efforts to safeguard the Merced have spawned a court battle over the future of development in Yosemite National Park's most popular stretch. The case may come down to the challenge facing all of America's parks: Should they remain open to everyone, or should access be limited in the interest of protecting them?
In November, a federal judge barred crews from finishing $60 million in construction projects in Yosemite Valley, siding with a small group of environmentalists who sued the federal government, saying further commercial development would bring greater numbers of visitors, thus threatening the Merced's fragile ecosystem.
"The park's plans for commercialization could damage Yosemite for future generations," said Bridget Kerr, a member of Friends of Yosemite Valley, one of two local environmental groups that filed the suit.
The government is appealing, fearing the ruling could force the National Park Service to limit the number of people allowed into Yosemite each day, a precedent it doesn't want to see echoed in other parks.
"I don't think we've ever had a ruling with these kind of implications," said Kerri Cahill, a Denver-based planner for the park service. "It's going to have a direct influence on the public who care about these places."
The case has Yosemite's most loyal advocates sharply divided over how to balance preservation with access to public lands. Even environmentalists can't agree on how to minimize the human footprint — some believe cars should be kept out entirely; others say visitors should have to make reservations in advance.
Yosemite was the first land in the country set aside for its scenic beauty, declared a public trust in 1864 by Abraham Lincoln. Its 1,200 square miles of granite peaks and towering waterfalls became a national park in 1890, and with few exceptions its gates have been open to all ever since, though backcountry permits are limited to minimize the human impact on wilderness areas.
The Merced itself is protected under the federal Wild and Scenic Rivers Act.
The current fight began when the Merced flooded in 1997, wiping out campgrounds and parking lots and damaging rooms at the popular Yosemite Lodge. The park service drew up a $442 million remodeling plan that included moving campgrounds, rerouting a key access road, rebuilding employee housing and upgrading hotel rooms on the valley floor.
Kerr's group and Mariposans for the Environment and Responsible Government sued, claiming aspects of the park's plans — including blasting part of the river canyon — threatened the Merced.
The groups also fear the costs of park upgrades would be passed on to visitors in the form of price hikes for hotel rooms and campsites, turning Yosemite into a playground for the rich.
Park officials say no such rate increases are planned. Accommodations now range from about $20 per night for a campsite to nearly $1,000 for a suite in the deluxe Ahwahnee Hotel.
Park spokesman Scott Gediman called the plaintiffs a "fringe group" pushing a radical agenda.
"They want us to set a quota for the number of visitors coming into the park, which is something we just don't want to do," he said.
Well-known conservation groups like the Sierra Club and Nature Conservancy aren't directly involved in the fight, though the Sierra Club was among more than 60 organizations that signed a legal brief supporting an earlier version of the suit.
Gediman said the number of visitors is falling and crowding isn't a problem except at the height of summer, when there's bumper-to-bumper traffic near popular sites like El Capitan, the 3,000-foot granite monolith rising from the valley floor.
In 1996, when the park had a record 4 million visitors, rangers shut gates when all parking spaces were filled. But last year, the nation's third-most popular park hit a 16-year low with 3.36 million visitors.
"This is the United States' version of the crown jewels, so why wouldn't we protect it as best we can?" said Peter Newman, a natural resources management professor at Colorado State University who filed a legal brief supporting the park service. "I've just never heard of any other plan that has been so contested."