Restoring Hetch Hetchy Valley: The role of modeling in policy



In 1923, following years of opposition and debate, the City of San Francisco, Calif., completed the O'Shaughnessy Dam, which flooded Hetch Hetchy Valley in California's Yosemite National Park. Today the future of Hetch Hetchy Valley is still debated.

Current discussion of restoring the valley has arisen within the state, and the idea of restoration has been largely supported by the use of system optimization and simulation modeling. Mathematical modeling provides thorough and systematic analysis of water supply systems and can suggest improvements to incorporate additional water uses or changing priorities. CALVIN (California Value Integrated Network),an economic-engineering optimization model, was one of two models used to evaluate the water supply and hydro-power implications of removing the O'Shaughnessy Dam [Null, 2003; Null and Lund, 2006].