Background

Don Pedro Dam 1922

First Don Pedro Dam Construction 1922

Formed in 1887, the two Districts are the oldest irrigation districts in California. They were created by a vote of the people in accordance with the laws of the State of California to provide water for agricultural purposes in their respective irrigation service areas which today total approximately 200,000 acres of trees, vines, row and forage crops.

Soon after formation, the Districts acquired a water diversion site on the Tuolumne River located downstream of the Don Pedro site along with “pre-1914” water rights; the Districts have added other water rights to these over time. An original Don Pedro Reservoir with approximately 290,400 acre-feet of storage and its associated Powerhouse were brought online in 1923 to improve water availability for the long growing season of the Central Valley and to bring electrification to a portion of this rural area. The Districts have been providing retail electric service to the communities’ farms, homes, municipalities, business and industry since that time. Today the Districts serve approximately 200,000 customers in a 1,000 square mile area.

The Tuolumne River has a long history of water planning. Concern over the need to withstand the effects of multiple dry years and the growing demand for electricity resulted in the Districts partnering with the City and County of San Francisco to develop the current Don Pedro Project. The New Don Pedro Project inundated the original dam and impoundment, and the
New Dam Filling

Water fills between the original and new dams (circa 1971)

resulting current Don Pedro Reservoir has a storage capacity of 2,030,000 acre-feet, over seven times that of its predecessor; the new Don Pedro Powerhouse constructed with the dam has a generating capacity of 203 MW. Planning for the enlarged Don Pedro began in the 1940’s and culminated when the Districts received the federal license in 1966 from the Federal Power Commission, predecessor to FERC.

The City and County of San Francisco contributed to the construction of the project but has no ownership interest in the dam, reservoir, or powerhouse, nor does it have any ownership of water in the reservoir. San Francisco participated in construction of the project in order to obtain a water banking arrangement in the new reservoir which provides it with greater flexibility in storing water for use at its upstream power facilities and for water supply. Construction of the project also relieved San Francisco of flood control responsibilities in the watershed thereby providing another important benefit for the City.

As the sixth largest reservoir in California, Lake Don Pedro provides extensive habitat for fish and wildlife, and has a wide recreation following. It is known for its bass tournaments and houseboating. Up to 500,000 visitors come to the reservoir each year to camp, boat, fish, and enjoy water sports such as skiing, wake boarding, and the use of personal watercraft.
Don Pedro Reservoir

Don Pedro Reservoir

 

Spillway

Don Pedro Spillway

 

Blue

Blue Oaks Picnic Area

 

Fleming

Fleming Meadows Swimming Lagoon

 

Highway

Don Pedro Dam on the Tuolumne River