Tuolumne Watershed Diversions without Hetch Hetchy Reservoir: Comparison of Interties to Cherry and Don Pedro Reservoirs

Without storing water in Hetch Hetchy Valley, additional conveyance facilities could allow the San Francisco Public Utilities Commission to divert supplies from storage in other Tuolumne River watershed reservoirs. The most obvious potential locations for additional conveyance are at Don Pedro Reservoir or at Holm Powerplant below Cherry Reservoir. Computer modeling, using a 73 year hydrologic record, indicates that either a Don Pedro Intertie or a Cherry Intertie would allow the SFPUC to deliver more than 95 percent of customer demand without diminishing system reliability. Some additional supplies would be needed in dry years to replace the loss of Hetch Hetchy Reservoir.