Unlike many other Georgia rivers that begin their journeys to the sea along the flanks of ridges in the relatively pristine confines of national forest lands, the Ocmulgee--a name that means "where water boils up" in Muskogee--rises inside Atlanta's I-285 perimeter highway as the South River in a jungle of asphalt and concrete. In fact, its very headwaters are buried beneath a hazardous waste site. Its other main tributaries--the Yellow and Alcovy--rise...