Opposition mounts against Pacheco Reservoir expansion project

GILROY — The Sierra Club is getting behind a lawsuit to stop a dam from being built in southern Santa Clara County.

The environmental organization announced it has joined a lawsuit with other plaintiffs such as the Amah Mutsun Tribal Band and nearby landowners in opposition to the Pacheco Reservoir Expansion Project.

The extensive pre-construction work alone would do harm to this sensitive area, according to the Sierra Club.

“They will be driving trucks all around and digging, causing sediment to run off into the riparian system,” said Katja Irvin, who works for the Sierra Club’s Loma Prieta chapter on water issues.

“That could have a big impact on some endangered species like red-legged frogs and tiger salamanders,” Irvin said.

There is an existing dam on Pacheco Creek in the hills just north of Highway 152 Pacheco Pass but the Santa Clara Valley Water District has plans to build a new dam upstream from the old one.

“It’s a huge expansion of an existing reservoir, about 25 times the size of the existing one, which would double our storage capacity in Santa Clara County,” said engineering manager Ryan McCarter.

McCarter says the dam is needed as the district looks to provide for the future water needs of Silicon Valley.

Its cost is an estimated $2.5 billion and would take a decade to complete.

“The project acts as a way to balance climate change by gathering it in wet years from the watershed and other supplies and using it in dry years,” McCarter said.

Katja Irvin says she supports the district’s other efforts to increase water storage and conservation but she says the dam is not needed and would increase water rates for consumers.

“We’re not saying no the San Luis Reservoir expansion. We’re not saying no the Las Vaqueros expansion. We’re not saying no to other ground water storage. We just think there are other opportunities for storage and less damaging dams,” she said.

The water district says it is preparing an environmental impact plan for the project and planning for the dam will go on even with the lawsuits pending.

“If we had this prior to 2017 when we had huge rains, we could have reduced our dependence on groundwater pumping, which is what we’re doing now in this drought,” McCarter said.