FLAGSTAFF, Ariz. (AP) – Yearly environmental reviews of a dam near the Arizona-Utah border that delivers water to millions of people would be impractical and aren’t required by law, a federal appeals court has ruled in rejecting a bid by an environmental group to force the reviews.

The U.S. Bureau of Reclamation operates Glen Canyon Dam in Page, releasing higher volumes of water during the winter and summer months when the demand for electricity peaks and less water when the demand drops. The Flagstaff-based environmental group, the Grand Canyon Trust, contends that the flow regime has harmed the endangered humpback chub and other resources downstream.

The group sought to have the bureau consult with the U.S. Fish and Wildlife Service each year on the environmental impacts of the dam as part of its annual operating plan. But a three-judge panel of the 9th Circuit U.S. Court of Appeals ruled Monday that the plan merely projects water releases and cannot be used to alter the established flow regime.

Allowing a challenge for each plan would be unduly cumbersome and unproductive in addressing environmental issues, and there’s no guarantee one challenge would be resolved before the next plan should be issued to Congress and the governors of Colorado River basin states, Judge Ronald Gould wrote for the court.

“There is no benefit to endangered species in having an unending judicial process concerning annual reporting requirements that Congress mandated,” he wrote.

While the Grand Canyon Trust didn’t prevail in requiring the annual environmental review, the ruling still provides an opening for challenging the operating criteria that was adopted in 1996, Neil Levine, an attorney for the group, said Tuesday. Environmentalists have said they want to see a long-term plan that includes steady water releases, mimicking the natural flow of the Colorado River.

“It’s undisputed in the Colorado River that the habitat has not improved for the chub and other cultural, recreational and archaeological resources,” Levine said. “They are still being harmed by the way the dam is being operated.”

Federal officials have been working on a long-term management plan for the dam. The proposals that have emerged so far have common threads in that they consider controlling nonnative fish like rainbow trout that feed on native fish, periodically flooding the Colorado River to build up sediment, establishing a recovery plan for the endangered humpback chub, controlling vegetation and monitoring cultural resources.

Dozens of federal and state agencies, American Indian tribes, environmentalists and the power industry have an interest in how the dam ultimately will be run.