SULTAN, Wash. -- A big public utility is on the cusp of building a hydroelectric-power plant on a picture-perfect stream in the Pacific Northwest, but the plan has yet to draw the usual opposition.

That is in part because the approved project, which involves building a dam on a tributary called Youngs Creek, is so small and remote that it has attracted little notice. It will generate only about 7.5 megawatts of power at its peak, enough electricity to power between 3,500 and 7,500 homes. By contrast, the much bigger Henry...