Environmentalists, property owners sue to block $2.5-billion dam project in Santa Clara County

The Pacheco Reservoir sits in eastern Santa Clara County.
The Pacheco Reservoir sits in eastern Santa Clara County. The artificial lake can currently hold about 5,500 acre-feet of water. Under the proposed expansion, that capacity would jump to 140,000 acre-feet of water.
(Santa Clara Valley Water District)
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As California endures water restrictions due to widespread drought, a proposed $2.5-billion reservoir expansion project in Santa Clara County promises to increase the amount of freshwater for more than a million people.

But a group of environmentalists and landowners claim in a lawsuit filed earlier this month that the local water district did not conduct the necessary environmental studies to determine how the project planned near Pacheco Pass would affect the region’s wildlife and undeveloped land.

For the record:

6:37 p.m. June 24, 2022A previous version of this story said the Sierra Club is a plaintiff in the lawsuit. The Sierra Club is not a party to the suit but supports the opposition to the dam project.

The coalition, which includes local residents and ranch owners, argues in its lawsuit filed in Santa Clara County Superior Court that the proposed project is “environmentally destructive, high-cost and high-risk” and would affect wildlife habitat, cultural sites and other historic sites.

The Pacheco Reservoir sits in eastern Santa Clara County. The artificial lake can hold approximately 5,500 acre-feet of water, but under the proposed expansion, that capacity would increase to 140,000 acre-feet of water, according to the Santa Clara Valley Water District, which is based in San Jose.


The Sites Reservoir plan would flood a bucolic valley north of Sacramento. Environmentalists say it would do little to solve California’s water woes.

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Last June, the district’s board of directors declared a water shortage emergency due to a county reservoir being drained to reduce earthquake risks.

Approximately 97% of California is experiencing severe drought, according to the latest report from the U.S. Drought Monitor at the University of Nebraska-Lincoln.

The lawsuit filed against the Santa Clara Valley Water District arrives as the project is in the planning phase. Construction is scheduled for 2024 and would be completed by 2032, but it’s unclear how the recent lawsuit would affect the timeline.

The Stop the Pacheco Dam Coalition, the group that filed the lawsuit, argues the water district did not study how the project would affect the local wildlife, cultural and historic sites or how the construction — with all its new infrastructure — would affect the area. Up to 1,500 acres would be flooded once completed and the new reservoir would be 25 times larger than the existing dam, according to the group’s lawsuit.

The federal government is telling seven states to make plans for drastically cutting water use along the Colorado River within two months.

June 20, 2022

The water district exempted the project from a review report to determine how geological surveys, including drilling, boring and other tests, would affect the local area, the group said in its complaint.

The district proposes to make 226 borings and dig 57 test pits i across 2,500 cubic yards of earth, according to the project description. There’s also concern that construction vehicles and helicopters that will be used by contractors during the test phase could disturb vegetation, plants and wildlife, according to the lawsuit. The group filed its writ of mandate in court on June 2 and is represented by Osha Meserve from the law firm Soluri Meserve.


They’re asking a court to temporarily block the district from moving forward with the project and order that it comply with the California Environmental Quality Act by conducting further environmental studies.

Matter Keller, spokesperson for the water district, said that when the project is complete, the expanded reservoir would help the federally threatened South-Central California Coast Steelhead trout. The agency says the project could supply up to 1.4 million residents with water for a year during an emergency.

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April 7, 2022

In a statement, Keller said: “Valley Water has complied with all environmental requirements for this work and will continue to do so for the length of this project.”