Dam operators could flood part of the Colorado River next year in an effort to save an endangered fish species, rebuild beaches, and kill part of an excessively large trout population. The flood plans were approved yesterday 17 to 1 by a federally appointed panel composed of every major group with an interest in the river. Wildlife officials, archaeologists, and rafting company operators all favor creating beaches along the river, which would be accomplished by allowing floods to deposit sediment along the water’s edge. After the flooding, river managers would alternate high and low flows every day to dry out the spawning grounds of the rainbow trout and destroy its eggs. As the final part of the plan, scientists would kill thousands of trout in a five-mile stretch of the river where the endangered humpback chub spawns. If approved by Interior Secretary Gale Norton, the experiment would be the fourth attempt to alter river conditions by dam manipulation. Some scientists feel that prior attempts to create beaches along the river resulted in short-lived successes at best.