Del Puerto Canyon is at risk of being destroyed by the Del Puerto Water District’s proposed dam project.

Nestled among the rolling hills of northern California’s Diablo Range, on the western edge of the San Joaquin Valley, lies the entrance to a vast and unique natural canyon.

The canyon is becoming increasingly recognized for its geological, biological, archaeological, and paleontological significance.

It should be a park with expanded recreational access, including for equestrian use.

Its current name of Del Puerto Canyon was given by Spanish explorers conducting their first inland traverse of the Central Valley, en route to the San Francisco Bay Area in the late 1700s.

They described the narrow rock opening in the mountain as “Del Puerto.”

After entering through that historic gateway where Del Puerto Creek emerges, the first of Del Puerto Canyon’s intimate valleys opens.

Flanked by steep rolling hills and perennial wildflowers of every color, the sights from the first few miles of Del Puerto Canyon are among the most spectacular in California.

Bobcats and mountain lions have been seen here, as well as burrowing owls, badgers, and countless other animals, including evidence of the endangered San Joaquin kit fox. One of the large golden eagle populations in the state resides right through the Gateway.

One of California’s iconic most endangered species, the California condor, was recently documented visiting Del Puerto Canyon. These sightings were not addressed in the first environmental impact report (EIR).

The beautiful canyon is now at risk with the construction of the proposed 260-foot-tall dam. The Gateway, along with a carved prehistoric pathway, would all be destroyed.

The Del Puerto Water District would use the dam to shut the Gateway and store water within the first five miles of the Del Puerto Creek drainage, which would mean no recreational access to the area.

The historic roadway would have to be re-routed away from the proposed reservoir and connected to Diablo Grande Parkway. The land is extremely rugged, so the rerouting of the road would be very expensive, and would damage the land extensively.

The real question, of course, is whether the benefits outweigh all of the costs.

Press accounts quoting Anthea Hansen, the general manager of the water district, estimated the cost at $400 to $500 million in 2017. Press accounts in December 2025 estimated the cost of this ridiculous project at $1.2 billion, a staggering 300 percent increase.

This is not a drinking water project. Water conservation and ground water storage are better, cheaper alternatives.

The trees, including the sacred cottonwood trees that are the last living link to the Hoyumne and Miumne Yokuts, would be cut down.

If built, water from the Del Puerto Reservoir would envelop an area of the Del Puerto Creek drainage that is known to be some of the fastest eroding in the state of California, with active landslides.

The Del Puerto Water District’s plans show the dam would be built along the San Joaquin fault line. Recent seismic activity near the project site was mentioned nowhere in the first EIR.

Interstate 5, the California Aqueduct, and the Delta Mendota Canal would be in danger of being washed away if there was a catastrophic failure of the dam, not to mention the risk of massive flooding that could tragically impact residents of Patterson.

The Patterson City Parks and Recreation Department, as well as previous city leaders, have all recognized the Gateway as an area of great cultural and ecological significance.

They've called for preservation of the area with recreational access for horseback riding, hiking, and mountain biking, as well as plans for an outdoor amphitheater.

Instead of being a benefit to the community, the Del Puerto Reservoir would have major impacts to access, safety, and recreation for a city of over 25,000 residents. There has been no meaningful outreach to the City of Patterson, particularly to underrepresented community members.

Opposition to the proposed Del Puerto Reservoir is growing as residents are becoming more aware of the hazards posed by the dam. Many are appalled at the potential loss of this natural treasure.

Del Puerto Water District is using unofficial approval from the Stanislaus County Board of Supervisors to request additional state funding for its dam project.

Just two weeks after receiving provisional approval from the Board for a roadway reroute connected to the project, the Del Puerto Water District sent a joint letter to the California Water Commission citing that approval to justify more funding through the Water Storage Investment Program (WSIP).

But the reservoir is not a done deal. Its environmental impact report (EIR) is still under review as a partially recirculated draft EIR—and it is still open to public comments.

Please submit a comment opposing the proposed Del Puerto Reservoir and dam!