When you think of the O'Shaughnessy Dam and the reservoir which provides up to 80% of the San Francisco Public Utilities Commission's (SFPUC) drinking water supply, it's important to note that the agency is committed to environmental stewardship. A key aspect of this is ensuring that the Tuolumne River remains a vibrant natural resource. This not only includes preserving life in the river like fish and other species, but also ensuring continued recreational purposes like rafting.