Up a remote canyon in the towering eastern Sierra, a Southern California company has an ambitious plan to dam the area’s cold, rushing waters and build one of the state’s first big hydroelectric facilities in decades. The project, southeast of Yosemite near the town of Bishop (Inyo County), faces long regulatory odds as well as daunting costs. But residents of the Owens Valley downstream and state environmentalists are not taking it lightly. The complex, as proposed in an application to the Federal Energy Regulatory Commission last month, is scheduled for mostly federal land at the edge of the Inyo National Forest, partly in the popular John Muir Wilderness.