More than 15,000 farmers and their supporters gathered yesterday in Klamath Falls, Ore., near the California border, to protest the loss of irrigation water to fish protected by the Endangered Species Act. The protesters formed a one-and-half-mile-long bucket brigade down the city’s main street, passing 50 pails of water from the Upper Klamath Lake into an irrigation ditch. The U.S. Bureau of Reclamation, which has a history of favoring farmers, last month decided to cut off water from 90 percent of the region’s farms, which together cover some 250,000 acres, to protect coho salmon downstream and two species of sucker fish upstream. Last week, a federal judge denied farmers’ request for an injunction to restore water deliveries. Farmers now are fighting to change the species act, and Republicans like Oregon Sen. Gordon Smith were on hand yesterday to cheer them on.