GOLD HILL, Ore.  When four dams on the Rogue River here were scheduled for removal, environmentalists predicted many benefits: more salmon and steelhead swimming upriver to spawn; more gravel carried downriver to replenish the riverbed; more rafters bobbing along 57 miles of newly opened water.

What they did not bargain for was the arrival this summer of a clutch of people, eager to sift through the tons of gravel for flakes of gold once hidden behind the dams.

Prospectors cluster slightly downriver from where the dams used to be. Their suction dredges blare together, in a discordant fanfare louder than lawnmowers.

Resentment now flows as freely as the river. Environmentalists and some riverside homeowners see the gold dredgers as noisy invaders rearranging the riverbed without care for the insects, fish and people who live in and along the Rogue. A state senator, Jason Atkinson, has announced that he will introduce legislation to ban the practice of dredging for gold; three state newspapers have editorialized in support of a temporary ban pending further study.