By Juan Pablo Galván Martínez and Stephen DePaschalis
Victory! In late August 2025, the Board of Valley Water voted to halt all spending and staff work on the Pacheco Dam project.
The current reservoir sits in the middle of Pacheco Pass and covers about 200 acres of land and about 5,000 acre-feet of water. It is north of Highway 152 and southeast of Henry W. Coe State Park.
Valley Water wanted to dramatically expand the reservoir to make it 20 times larger.
Pacheco Creek. Photo: Scott Hein
Their decision to halt the project follows the California State Water Commission refusing to assign any money to the project because of lack of progress and increasing costs.
That same week, the federal Bureau of Reclamation stated that they would not spend money on the project and would not store water in the expanded reservoir.
These back-to-back blows and the relentless work of the Stop Pacheco Dam Coalition finally made the Board put an end to this insane project.
The proposed reservoir would have blocked a critical Diablo Range wildlife corridor. Photo: Scott Hein
Save Mount Diablo has been working to oppose this harmful project for years and brought decades of experience in responding to land use threats to help in the fight.
However, our partners, including landowners, conservation organizations, and decision makers did most of the heavy lifting in fighting against this bad project.
This new larger reservoir would have blocked a designated critical wildlife linkage in the ecologically diverse Diablo Range.
It also would have flooded 150 acres of protected land on The Nature Conservancy’s Romero Ranch conservation easement area, as well as a portion of Henry W. Coe State Park, land that is designated to be permanently protected.
A bald eagle soars over the Pacheco Pass area. Photo: Scott Hein
The costs of the project were completely unreasonable too. When Valley Water applied to the state seven years ago for funding, it said the new reservoir would cost $969 million.
Since then, costs have tripled to $2.7 billion. With inflation and finance expenses, final costs could have been above $5 billion.
Pacheco Pass. Photo: Scott Hein
To fight against this project, Save Mount Diablo spoke at public meetings where agencies such as the California Water Commission discussed the project.
After hearing comments from Save Mount Diablo and others, California Water Commission members expressed concern over the delays and the funding being held hostage by Valley Water, instead of being spent on viable projects.
We also recorded beautiful images and video of the areas that would have been drowned if the Pacheco dam and previously proposed Pacheco Reservoir expansion would have proceeded.
White globe lily at Pacheco Pass. Photo by Scott Hein
Many thanks to the landowner and Stop Pacheco Dam Coalition coordinators for facilitating our tour and helping us share the beauty and importance of this amazing place with the public.
This is a huge victory, and while we and our partners will remain vigilant in the future if this project ever comes back in some form, we savor this win and the end of a threat to this crucial wildlife corridor and beautiful part of the Diablo Range.
Thank you to our partners and supporters for making it possible!
