New reservoir in Stanislaus County could move forward with approval of final study
The Del Puerto Water District board is set to vote Wednesday on approving a final environmental impact study on a much-disputed storage reservoir in western Stanislaus County.
The proposed 800-acre reservoir just west of Patterson stirred debate among vocal opponents and supporters at public meetings before the COVID-19 crisis deflected attention away from the project.
The board is scheduled for a regular meeting on Zoom. It’s not holding meetings in public because of the coronavirus outbreak, but the online meeting will provide opportunity for public comments. The public can watch the Zoom meeting live, starting at 8:30 a.m. Instructions for joining are on the agenda at the district’s website, www.delpuertowd.org.
Anthea Hansen, general manager of Del Puerto, said approval of the EIR would clear the way for project partners to complete designs for the dam and seek permits from a host of state and federal agencies.
Rep. Josh Harder, D-Turlock, secured funding for feasibility studies on the reservoir and sponsored legislation that will help it qualify for future federal infrastructure loans.
A coalition of groups including Save Del Puerto Canyon, Friends of the River, Sierra Club Mother Lode Chapter and others, said the risk of landslides was understated in the draft environmental study. At least seven landslides are mapped in the portion of Del Puerto Canyon that would be inundated by the dam, plus additional slides could form as the reservoir water saturates the canyon slopes, the group contends.
The group said landslides threaten to create a tsunami that could overtop the dam. Residents who have opposed the project fear a dam failure would unleash serious flooding in Patterson, which has 23,000 residents.
David Keller, a former mayor of Patterson, said the project would put the entire city in a dam inundation zone, requiring homeowners to disclose that to buyers. He said a map provided by the water district shows a catastrophic failure of the dam flooding the city with 10 to 15 feet of water.
Keller, who is running for mayor in the current election, said one of his main concerns is the city was not named the responsible agency for the environmental review.
Study responds to landslide threat
In regard to landslide threat, the final environmental study says the landslides are slow moving and likely range from active to dormant. It says the closest landslide on maps is about three-quarters of a mile from the foot of the dam embankment.
According to the study, landslides are typical issues for reservoirs and can be stabilized with subdrains, retaining walls and other mitigations.
The review also responds to comments and concerns raised about impacts on wildlife, natural features and Native American artifacts in Del Puerto Canyon.
Hansen said the final EIR responds to the issues raised at public meetings and provides a lot of information on dam safety. The district posted a video discussing the safety of dams.
“The work we have done so far strongly indicates that we have a very good project that could change things in the Central Valley in terms of improving local storage and improving our water supply situation,” Hansen said.
According to proponents, the reservoir storing up to 82,000 acre feet of water will provide for more reliable water deliveries to farmers south of the Sacramento-San Joaquin river delta, increase water supplies for when crops need it the most and improve management of groundwater.
Water pumped from the nearby Delta-Mendota Canal would be stored behind the dam.
“We have worked hard to address the concerns in the community and plan a safe, reliable water storage reservoir,” Chris White, executive director of the San Joaquin River Exchange Contractors Authority, said in a news release. “This project will also help stabilize groundwater supplies for many of the communities on the west side.”
Del Puerto Water District and the Exchange Contractors funded the environmental review and planning for the reservoir, while additional support for design and studies came from the 2016 Water Infrastructure Improvements for the Nation (WIIN) Act.
Construction on the dam next to Interstate 5 could begin within two years and be completed in 2028.
This story was originally published October 19, 2020 at 2:19 PM.
