Two conservation groups celebrated the ruling, which effectively halts about $60 million in construction projects for at least two years.

Yosemite officials, still reeling from the decision, said it could have “huge negative impacts” on the park’s efforts to accommodate the 3 million visitors who travel there each year.

“The fact that now we can’t repave a road, with winter coming on, is just devastating,” said Scott Gediman, a park spokesman. “Sure you can argue about campgrounds or building the lodge, but what about when you’ve got paving on a road that’s literally falling apart?”

The order, issued in a U.S. District Court in Fresno, directs the park service to immediately stop nine projects included in the Yosemite Valley Plan, a grand scheme to develop the park’s amenities that has been the subject of a lengthy legal battle.

While the case likely will be appealed, legal scholars said it was not surprising that part of the park’s $442 million remodeling effort now figured in a lawsuit.

“Anything that’s done in a national parks system, particularly those that are beloved and heavily visited, is likely to be challenged by some group of stakeholders,” said Richard Frank, an environmental law professor at the University of California, Berkeley’s Boalt Hall School of Law. “We’re seeing more litigation of this kind than ever before.”

Park officials now must devise a legally valid plan to protect the Merced River before going ahead with projects to upgrade the Valley’s sewer system, redevelop Yosemite Lodge and repave roads.

“We need to put in place some kind measure to keep the Valley from being loved to death,” said Barbara Boyle, a spokeswoman for the Sierra Club in Sacramento. “The overall problem that we face in Yosemite is how to reduce the footprint of the development and commercialization in the park. How many people is just too much?”