More than 275 Utahns filled a large meeting room in the Salt Lake Hilton Monday night, laying out some highly differing agendas for a federal review of the operation of Glen Canyon Dam.

Power user groups, the Central Utah Project's planners and environmentalists were out in force for the hearing on the development of an environmental impact statement about the dam. This was the first of seven hearings throughout the nation to define the scope of the statement, and all sides used it as a platform for their agendas.The final statement is supposed to be finished by December 1991.

Generally, power users and the CUP (which benefits financially from the dam's power sales) favor continuing the status quo of dam operation, which has damaged Grand Canyon National Park downstream along the Colorado River. They said other options to protect the environment - including building up beaches artificially and limiting the numbers of people in the canyon - should be examined.

Environmentalists favored returning flows from the dam to as nearly natural a level as possible, reducing the huge daily fluctuations that result from generating power based on peak demand periods. Some also want a return to flows similar to spring runoffs and low water levels in the late summer.

A sampling from among the 40-plus Utahns who signed up to testify:

-Carolyn S. McNeil, general manager of the Intermountain Consumer Power Association, which furnishes power to 300,000 people in the West: "Supply disruptions, transmission bottlenecks, market conditions and economic impacts upon electric customers must be fully evaluated as a consequence of changing operations of the dam and weighed against alternative solutions."

-Rudy Lukez, conservation chairman of the Sierra Club's Utah Chapter: "It would be real nice to see the dam removed in the next few years." Failing that, the dam's operations should be modified so that flows from it match natural flows.

-Clifford Barrett, Salt Lake City, the former regional director of the Bureau of Reclamation, who now represents the Colorado River Energy Distributors' Association: Beaches could be planed down so they are not as likely to erode from heavy flows. Perhaps "sands from the river could be dredged up" to restore beaches and create new beaches.

-Sharon Hester, Salt Lake City: "The beaches are disappearing at an alarming rate." Half of the natural beaches are already gone, and this is "an affront to our national park system."

-Jeffrey Appel, Trout Unlimited and Utah Wildlife Leadership Coalition: The study should cover the entire dam system along the Colorado River, not just downstream from Glen Canyon Dam.

-Ken Maxey, Sandy, area deputy manager for Western Area Power Administration: Look for other methods of restoring the environment, like mechanical construction and stabilization. The Park Service should re-evaluate its policies of allowing so many rafters on the river.

-William B. Smart, a director of the Grand Canyon Trust and a retired chief editor of the Deseret News: Damage in the past five years is astounding. A suggestion to build concrete platforms for camping shows "contempt . . . and such ignorance of what the wilderness experience is meant to be." Close attention must be given to repairing the quality of the recreational experience of the Grand Canyon.

-Ted Olsen, Ephraim, vice president of Intermountain Consumer Power Association: "Maybe parity starts at the pocketbook." Everyone who benefits from the dam should pay for restoring the environment. "Not all of this should be placed on the backs of the power users."