Frequently Asked Questions About Hetch Hetchy

What is Hetch Hetchy Valley?

Hetch Hetchy is a glacier-carved valley in California's Yosemite National Park. Naturalist John Muir called it a "wonderfully exact counterpart" of Yosemite Valley, likening its waterfalls and sheer granite walls to those in its more famous twin. In the early 20th century, after a historic struggle, Hetch Hetchy Valley was dammed by San Francisco to expand its water supply system.

Why should the restoration of Hetch Hetchy Valley be explored now?

The San Francisco Public Utilities Commission (SFPUC) is beginning a multi-billion dollar overhaul of its water system. While many of the elements in its Capital Improvement Program involve fixing old pipes, some elements involve system expansion and significant changes in how the SFPUC will store, move and treat water. The changes provide an opportunity to simultaneously consider alternatives that would allow for the restoration of Hetch Hetchy Valley.

Why is Environmental Defense working to restore Hetch Hetchy Valley?

Environmental Defense is a leading national nonprofit organization that links science, economics and law to create innovative, equitable and cost-effective solutions to environmental problems. We have been committed to efficient water and energy management throughout California and the West for more than 30 years. Restoring Hetch Hetchy Valley could simultaneously address water needs for the future, demonstrate 21st century approaches to water management and recover an important environmental landmark.

What happens next?

Our study is the starting point of a dialogue to consider alternatives that will make possible the restoration of Hetch Hetchy Valley. We call on local, state and federal officials to review our findings and involve the public in a comprehensive plan to restore the valley. With support from a dedicated public, visionary leadership from public officials and stakeholders' willingness to explore new arrangements, this American paradise can be regained.

Water Supply

Without Hetch Hetchy Reservoir, where would residents of San Francisco and other Bay Area communities get their water?

The SFPUC would still receive the vast majority of its supplies from the Tuolumne River, diverted either from Tuolumne River flows or stored supplies from other downstream reservoirs, including Eleanor, Cherry and Don Pedro.

Is it physically possible simply to use other existing reservoirs?

Yes. Constructing a connection from the lower Tuolumne River to the SFPUC's aqueduct will allow more efficient use of existing reservoirs, nearly making up for the loss of storage at Hetch Hetchy. Some additional supplies would be needed in the driest years to assure dependable deliveries. These replacement supplies would amount to less than five percent of total supply.

Where would these replacement supplies come from?

Our study presents three principal alternatives (though others exist):

1. increasing local Bay Area storage capacity,
2. transfers from agriculture, and
3. groundwater banking.

The SFPUC itself lists these alternatives in its Water Supply Master Plan (2000).

How did you conduct the research for your Hetch Hetchy Solutions Study?

We developed a water model called TREWSSIM (Tuolumne River Equivalent Water Supply Simulation), combining features of the planning models used by the SFPUC and state and federal agencies. TREWSSIM simulates operation of the SFPUC system with and without Hetch Hetchy Reservoir.

Does your study use the same methods as the recent U.C. Davis study?

No. Our studies are similar but different in key respects, such as how water supply reliability is addressed. The U.C. Davis study, using its CALVIN model, assigns economic values to reservoir storage and, as a result, recommends that the system operate at lower storage levels in dry years. Our study uses fixed minimum values for reservoir storage that are similar to the values that the SFPUC uses.

What about water quality? Doesn't Hetch Hetchy provide some of the best water quality anywhere?

The Tuolumne River does have excellent water quality, especially when diverted high in the watershed. However, it is not currently filtered, as almost all water systems nationwide are. Under our plan, the San Francisco Public Utilities Commission, which already filters its local supplies, would filter all its supplies. At the tap, the water is likely to be safer, at least with respect to pathogens such as giardia and cryptosporidia.

Replacing Hydropower

How much electricity does the SFPUC System provide?

The SFPUC operates three powerhouses on the Tuolumne River. Their annual production is highly variable, depending on factors such as precipitation, the timing of spring snowmelt and water supply operations. Over the last 30 years, their combined output has ranged from 544 to 2,391 million KWh per year, averaging about 1,700 million KWh annually. This is enough energy to light about 170,000 homes.

Who uses the energy?

In 2002 the SFPUC used less than half of the system's output, and sold most of the rest to the Turlock and Modesto Irrigation Districts (TID and MID). The Raker Act requires San Francisco to sell excess energy to the Districts. In San Francisco this energy is used for public buildings and services such as the municipal railway (MUNI). The Pacific Gas and Electric Company provides electricity to homes and businesses in the City.

How will hydropower generation be affected if the valley is restored?

San Francisco would still be able to produce energy using at least two of its three powerhouses. The system's average annual output would decline by 20-40% depending on whether or not Kirkwood powerhouse can be modified to operate without O'Shaughnessy Dam. Generation would fall by about one third at Moccasin powerhouse, while Holm powerhouse would not be affected. In all but the driest years the system would still produce enough energy to meet San Francisco's current public sector needs, but less electricity would be available for sale to the Turlock and Modesto Irrigation Districts and others.

How can the energy be replaced?

San Francisco, TID and MID have several options. They could avoid the need for the lost hydropower by increasing investments in energy efficiency. Other options include purchasing more energy under long-term contracts or building new power plants, as TID and MID have recently done. The amount of hydropower that would be lost from restoring the valley is dwarfed by the California Energy Commission's estimates of the statewide potential for energy efficiency and new renewable energy as well as new power plant construction.

Are there "green" sources of replacement energy?

The cleanest alternative is upgrading equipment and buildings to use less energy. While considerable untapped conservation potential remains in California, some new generating capacity would probably be required. Wind and solar power are the most abundant renewable energy resources in California. Highly efficient new gas-fired power plants are the least polluting fossil fuel-fired alternative. Under existing air quality regulations, new gas-fired plants in California should cause no net increase in air pollution, but special arrangements are needed to offset their greenhouse gas emissions.

How much will it cost to replace the energy?

We estimate the cost of replacing hydropower from the SFPUC system would range from $18.6 to $38.0 million annually. This estimate includes the cost of building and operating new gas-fired or wind-powered generation facilities in California. To the extent that the need for the lost energy is replaced with energy from existing facilities or displaced by new investments in energy efficiency, costs may be lower.

Will reducing SFPUC hydropower production affect closure of the Hunter's Point power plant?

No. Hunter's Point is an obsolete and dirty power plant that should be closed. If claims made by those who seek to keep it open awhile longer in order to assure local reliability are credible, then the City and the generators should move quickly to increase transmission capacity and local alternatives to the plant. Hetch Hetchy operations are irrelevant to this controversy. Delays in closing Hunter's Point have been a function of a bottleneck in the transmission lines that feed energy into San Francisco via the Peninsula, not the City's overall power supply.

Legal and Institutional Considerations

What laws need to change to make restoration happen?

Congress must amend the Raker Act while the State of California likely will need to affirm new water use, diversion and storage arrangements. San Francisco, its wholesale customers, the Districts and others will need to negotiate new agreements that address the legitimate water and power demands of all. State and/or federal action will be needed to assure that those who will benefit from the valley's restoration share the cost of making it possible.

What public agencies have to approve the restoration plan?

Important agencies at the federal level will include the National Park Service, the Corps of Engineers, the Bureau of Reclamation and the Environmental Protection Agency. At the state level key actors are the Department of Water Resources, the Department of Fish and Game and the Department of Health Services.

Restoration Logistics

Can the valley be restored to its original state?

A 1988 National Park Service report that investigated a range of alternatives for restoring the valley concluded that if the reservoir were drained the valley would eventually rebound. Within five years, mammals, amphibians and reptiles endemic to the area would return to the valley. After 10 years, meadows, willow thickets and conifer groves would begin to resume their original pattern. After 50 years, the valley would begin to appear as it once did. Over the next century, trees would mature, the bathtub ring on the valley's walls would gradually fade away and Hetch Hetchy would once again resemble the "grand landscape garden" that John Muir celebrated.

Who will be responsible for overseeing restoration?

Since the valley is a part of Yosemite National Park, the National Park Service would most likely oversee the restoration program. Given the scale and importance of this effort, it is likely that restoration experts from around the world would participate as well.

Costs and Benefits

How much will it cost to restore the valley?

Our study focuses on the most challenging and costly components of restoration -- replacing the water and power services provided by O'Shaughnessy Dam. Taking key uncertainties into account, we estimate these costs would range from $500 million to $1.65 billion on a net present value basis. Not included in these estimates is the cost of removing O'Shaughnessy Dam, restoring Hetch Hetchy Valley or building facilities to accommodate the visitors from across the United States and around the world that would flock to see the valley and its unprecedented restoration. A more thorough public study will be needed to calculate the total cost of bringing back the Hetch Hetchy Valley.

What are the benefits of restoring the valley?

Many people would benefit from bringing back Hetch Hetchy Valley. People could be involved with restoration of Hetch Hetchy Valley from the time that it is drained. Volunteers could assist with planting native vegetation and removing exotic species. Beginning shortly after the time the reservoir is drained, the millions who visit Yosemite National Park each year would have the chance to stand on the valley's floor and gaze up at its cliffs and waterfalls. Over time visitors would be able to witness the recovery of the valley's plant and animal life and generations of students and researchers would get to study the valley's unprecedented process of renewal. Gateway communities in Tuolumne County would benefit from the tourists' expenditures. Also sharing in the benefits of restoration would be supporters of national parks, wildlife and conservation who would find satisfaction in preserving a national treasure for future generations. Indeed, in government sponsored cost-benefit analyses of recent proposals to restore rare landscape features such as Olympic National Park's Elwah River and California's Mono Lake, estimates of "existence value" have significantly exceeded the projected value to direct users.

Who will pay?

Determining who should pay the costs will be a major factor in developing a plan to finance the valley's restoration. Millions of people nationwide and around the globe will share the benefits of recovering a vital part of one of America's most revered national parks. The valuable water and power services now provided by Hetch Hetchy Reservoir are shared by a much smaller number of Bay Area and Central Valley residents, and they stand to lose the most from restoration, if they are not compensated for those losses. As restoration alternatives are further explored and refined in the public process, a variety of funding sources should be examined to find an equitable way to pay for restoration. Sources could include federal and state governments, current users of Tuolumne River water and hydropower, user fees from park visitors and philanthropic donations.

Posted: 08-Aug-2007; Updated: 08-Aug-2007