You're a grass-roots coalition of American Indian and environmental groups. You're fighting the University of Arizona and a congressman. The future of Mount Graham hangs in the balance. How do you level the playing field?

You call in Pearl Jam.

The alternative rock group fired off a letter last week to President Clinton, praising him for vetoing a congressional bill that would have allowed the university to build a third telescope atop Mount Graham.

"By vetoing the Internal Appropriations Bill, you have firmly reinforced your commitment not to compromise on the environment," said the letter signed by Pearl Jam's lead singer Eddie Vedder and the rest of the band.

"We, like you, oppose any legislation that would allow the University of Arizona to be exempt from environmental laws in order to build an observatory on Mt. Graham, on top of the sacred sites of the Apache people."

The letter wasn't the first time Pearl Jam has come to the defense of the 10,477-foot mountain. In 1993, the band held a concert in Phoenix to raise money for groups opposing telescope construction on the mountain.

UA officials were unsure what to make of Pearl Jam's opposition to their project.

"I don't want to offend any kids who like Pearl Jam," said Jim Slagle, the project's director, who prefers classical music to grunge. "There's nothing I can say to (the letter). This is a good project, and we're going to press on."

Doug Nick, press secretary for Rep. Jim Kolbe, R-Ariz., is sponsoring the amendment to allow additional telescope construction and had little more to say about Pearl Jam's letter.

"We'll get some good music working out of this at least," Nick said.

In the letter, Vedder and the band urged Clinton not to waiver in his commitment to the environment and the San Carlos Apaches, who consider Mount Graham a sacred mountain.

Telescope opponents appreciate Pearl Jam's support of their cause, believing the group can reach many people who may otherwise be unaware of the Mount Graham controversy.

"Eddie Vedder has gone to the mountain," said Anne Carl, a member of the Student Environmental Action Committee at the UA. "He wasn't of the rock star mentality and full of himself. He was really down to earth."

Vedder and band members were unavailable for comment yesterday, said a spokesman for Curtis Management, which manages the Seattle-based group.