Diablo Canyon desal expansion plan heads to SLO County supervisors

An expansion of Diablo Canyon nuclear power plant’s desalination plant to provide 1,300 acre-feet of water for the South County is feasible but could cost as much as $36 million to build.

The San Luis Obispo County Board of Supervisors is scheduled to hear an update of the proposal Tuesday and decide whether to direct county public works staff to move ahead with the project.

At previous hearings, supervisors as well as city leaders in the Five Cities area, which would receive the water, and plant owners at PG&E have expressed support. The area faces a potential water crisis within the next two years because of low water levels in Lopez Lake, the area’s main water source; saltwater intrusion into the groundwater basin; and unreliable State Water Project deliveries in past years.

“Therefore, all aspects of this project will need to be expedited if it is to be part of the immediate solution,” said Mark Hutchinson, deputy county public works director.

Supervisors on Tuesday will be asked to approve a budget allocation of $900,000 to begin the planning and permitting process, though the cost of the project ultimately will be borne by its participants over a 20-year lifespan.

The participating water purveyors are the cities of Pismo Beach, Arroyo Grande and Grover Beach, as well as the Oceano and Avila Beach community services districts.

The project would consist of expanding Diablo Canyon’s reverse osmosis desalination plant to produce as much as 1,300 acre-feet of additional water per year and building a 7-mile pipeline to transport the water to the Lopez Lake water system.

Another seven miles of existing pipeline would need to be upgraded. A pump station and other pipe fittings and equipment also would need to be installed.

A feasibility report for the project looked at three options: one that would produce 500 acre-feet a year, and two that would produce 1,300 acre-feet. Construction costs for those options range from $22 million to $36 million.

However, county staff says the most feasible option is a middle-of-the-road one that has a construction cost of $30 million but has the lowest cost per acre-foot, at $2,800 to $3,300 per acre-foot. That price range would make it some of the most expensive water in the county but would still be in an acceptable range, Hutchinson said.

Getting the project permitted and built in the optimal two years will be a challenge. It will need the approval of the county and the California Coastal Commission.

“To do an environmental impact report typically takes a year, and then the Coastal Commission can take another year to make its decision,” Hutchinson said. “So we are looking at 18 months to two years, and then another couple of months for construction at a minimum.”

However, just in time for Tuesday’s meeting, the county received some good news that could give the project some breathing room. On Friday, the state Department of Water Resources announced that the allocation from the State Water Project will increase from 30 percent to 45 percent this year, giving the South County some much-needed drought relief.

“The increase from 30 percent will provide increased flexibility for State Water Project contractors, who have not received more than half their allocated supplies since 2012,” said Terry Erlewine, State Water Project manager.

This story was originally published March 19, 2016 at 4:11 PM with the headline "Diablo Canyon desal expansion plan heads to SLO County supervisors."