“We have an amazing opportunity to return Yosemite’s second crown jewel to the American people,” said Tom Graff, Environmental Defense California regional director. “Environmental Defense believes this study lays a credible framework for local, state and federal officials to consider restoring the valley as the Bay Area spends billions of dollars to retrofit its water supply system.”
The study, Paradise Regained: Solutions for Restoring Yosemite’s Hetch Hetchy Valley, provides solutions for continuing to bring water from the Tuolumne River to the San Francisco Bay Area without storing the river water in Yosemite’s Hetch Hetchy Valley. The group offered the study as the San Francisco Bay Area is undertaking a $3.6 billion retrofit and expansion to its Tuolumne River supply system. “This comprehensive overhaul of the system provides a once-in-a-lifetime opportunity to evaluate whether drinking water and power supplies can be met without storing water in Yosemite National Park,” said Spreck Rosekrans, senior analyst for Environmental Defense. “We believe our study shows that it can.”
Using information and methodology provided by the San Francisco Public Utilities Commission (SFPUC) and the State of California, Environmental Defense created a water-planning model to ensure that the water system continues to meet present and projected needs for San Francisco and its suburban customers. The group concluded that San Francisco could continue to receive the majority of its drinking water and hydropower generation from the Tuolumne River by using Eleanor, Cherry and Don Pedro reservoirs also located on the Tuolumne River. A new pipe or “intertie” connecting Don Pedro to the City’s water delivery pipes would be required.
“Hetch Hetchy Reservoir is less than 25% of the SFPUC’s total system storage,” said Rosekrans. “The results of our water modeling show that other reservoirs are sufficient to meet full delivery objectives in four out of five years. Our study identifies a variety of additional water resources that can be used as a buffer in the dry years.” The water model, Tuolumne River Equivalent Water Supply Simulation (TREWSSIM), shows that in the driest one out of five years, approximately 18% of additional supplies would be needed in order to meet water delivery objectives while maintaining sufficient reserves.
The study indicates that these additional supplies could be obtained by increasing local Bay Area storage capacity, purchasing from agricultural districts, and using groundwater banking (storing supplies in existing underground reservoirs). The San Francisco Public Utilities Commission has already outlined these additional supplies as options in its Water Supply Master Plan (2000).
The City of San Francisco also uses the Tuolumne River to generate hydropower for energy supply to its public buildings and municipal facilities such as the San Francisco Airport. In 2002, an average year, the SFPUC used slightly less than half of the system’s output, and sold most of the remaining output to the Turlock and Modesto Irrigation Districts. The Environmental Defense study found that San Francisco would still be able to produce energy using at least two of its three powerhouses, reducing generation output by 20-40%. The group indicated that the lost energy could be replaced through conservation, renewable resources or through supplies from one of many new gas-fired power plants being built in California.
“The small amount of energy lost from restoring Hetch Hetchy Valley could be replaced through energy conservation, new renewable energy production or by less than one-fifth the power from just one of the dozen new power plants that have come online in California since 2001,” said Dr. Nancy Ryan, senior economist for Environmental Defense. “That’s a small investment to make in order to restore Hetch Hetchy to the national park system for people to enjoy for countless generations.”
Environmental Defense estimated costs for adding the intertie and making retrofits to the system leading to restoration of Hetch Hetchy Valley. Further, the group recommends that local, state and federal agencies should negotiate to cover these costs and make new arrangements that respond to the legitimate demands placed on the Tuolumne River for water supply and power production.
“Environmental Defense recognizes that our Hetch Hetchy solutions study presents a number of challenges to water agencies and elected officials as San Francisco undertakes its Capital Improvement Program,” said Graff. “But Californians over many years have been leaders in solving tough environmental problems. Now is the time to unleash that same ‘can-do spirit’ in order to restore Hetch Hetchy Valley to its rightful place in Yosemite National Park.”