Several changes to an ocean desalination project proposed near Doheny State Beach to help generate drinking water for South Orange County were discussed Wednesday, Oct. 7, by the California Coastal Commission, with the modifications given the green light.
Approved changes will move the slant wells, which will source water from subsurface intake wells buried beneath the ocean floor, to the north day use area of the state beach, away from the campgrounds as previously proposed.
The project aims to tap seawater to lessen the dependence on imported water, with the South County Water District estimating the ability to make up to 5 million gallons per day of drinking water supply using a first-of-its-kind system in the state.
The desalination plant would sit at Pacific Coast Highway and Stonehill Drive, next to San Juan Creek, within 100 yards of existing regional water transmission lines. SCWD proposes to build the facility on property it owns, with much of the infrastructure already in place.
More details about the financials and timeline of the project were also discussed by water district officials, with delays pushing the next steps in the process from this fall into next year.
That means, if approved by SCWD officials and partners next year, the desalination system could be expected to be running by 2030.
The latest guaranteed maximum price for the project is estimated at $296 million, officials said. That price tag covers finalizing the design and building the project.
The main reason for the delay is the potential for an additional $63 million federal grant from the U.S. Bureau of Reclamation early next year that would help cover a significant portion of the overall project cost, South Coast Water District General Manager Rick Shintaku said.
Current and potential partner agencies are waiting on the decision before committing, he said.
“Extra time gives us, and them, time to work through the numbers with policy bodies and governing boards,” said Marc Serna, the water district’s assistant general manager and chief engineer.
The added time also lets partner agencies assess rate impacts for their customers before committing, Serna said.
Already, the project has received $40 million in state and federal grants. A decision on the new grant funding is expected in early 2027, and if approved, it would allow SCWD to approach partners with a lower per unit of water cost, which has not yet been calculated, Shintaku said.
“That would be a game changer for the unit cost for the project,” said Shintaku. “Overall, we’re feeling good about it.”
When the project was first approved by the Coastal Commission in 2022, cost estimates were $140 million, increasing to about $236 million earlier this year.
The latest increase of $42 million is for an on-site power generator using solar power and energy generated at the nearby county landfill, a decision to invest in innovative infrastructure, Shintaku said. “The payback is very soon and we’ll start saving significant money in the long run.”
Another reason behind the delay is a concern about the upcoming El Niño winter, with a critical portion of the project site sitting on the beach, Shintaku said. If construction commenced and storms delayed work, a contractor could collect interest — roughly $35,000 a day — while idle, he said.
Annual operating costs of the desalination system are currently estimated to be $11 million in the first year of operation, covering power, labor, materials and chemicals.
Acciona, which was chosen with J.R. Filanc Construction to design and build the project, would operate the plant under contract for 15 to 30 years, and operating costs in future years are still being negotiated, Serna said. Costs may increase in future years due to funding for repairs and replacement of aging equipment.
SCWD has yet to release monthly projected costs for an average home, but officials said the board of directors set rates through a public Prop 218 process, in which every customer receives notice and a chance to weigh in. The grant should reduce those estimates.
The changes discussed by the Coastal Commission on Wednesday to move the slant wells from the north day use area are due to new geologic studies that show the campground site could not reliably supply enough seawater.
The California State Lands Commission will also weigh in on the changes on Oct. 21 and the Regional Water Quality Control Board in early 2027.
By April to early summer, the needed approvals should be in place, and SCWD will have an answer to the grant funding so partner agencies can make an informed decision, Serna said.
Doheny State Campground, one of the most popular in the State Parks system, wouldn’t need to be closed for the construction before fall 2027.
Even though the slate wells are moving, the renovation planned for campgrounds will still be happening, SCWD officials said.
Campground design and permitting continue with California State Parks, with an estimated 225 parking spots to be closed in the day-use area, as well as a picnic area and the campgrounds during the nearly two years of construction.
Coastal Commissioner Caryl Hart asked that mitigations be made for the loss of parking, especially during the busy summer months.
Shuttles to make up for the loss of parking are being discussed, as is year-round camping at San Onofre State Beach, currently closed in the off-season, commission staff said.
Hart requested that, once the mitigation and campground upgrade plans are complete, all of the plans return as one whole package.
“While we may have approval today for the movement of the slant wells, it’s the whole package we really need to consider,” she said.
There is no permanent loss of parking proposed in the north day-use area and SCWD will replace and upgrade the public restroom and restore the picnic area, officials said.
The desalination project dates back to 2004, when the Municipal Water District of Orange County explored ideas for tapping ocean water for drinking supplies.
South Coast Water District, based in Laguna Beach, took over the planning in 2015.
Using the pipelines buried under the ocean floor is the preferred method, officials have said, because it would have little impact on marine life. Brine, the saltwater left over from the desalination process, will be mixed with treated wastewater in an existing outfall pipe and discharged two miles out into the ocean.
The Doheny plant would be the first commercial-scale desalination project to use slant wells designed to collect ocean water from beneath the seafloor and pull it through sand, reducing risks to sea life that have been concerns for other proposed desalination plants.
The project would give South Orange County residents a locally controlled source of water, which would mean more reliability and an assurance of a continuous supply, Shintaku said.
Ninety percent of South Orange County’s water is imported from the Colorado Basin and Northern California, treated at a facility in Yorba Linda.
If the pipelines that run to the area were to rupture or go out of service, the district would have enough emergency supply to last 10 days, Shintaku said. With locally sourced water, the area would have a 60-day supply, he said.