County desalination study presents five alternatives; Cambria option would need new outfall and could cost hundreds of millions

Krollo Engineers project engineer Anthony Simo presented the San Luis Obispo County desalination feasibility study to the Cambria Community Services District board on June 24, describing five concept alternatives that range from small, local facilities to regional plants producing as much as about 7,800 acre-feet annually. The study places Cambria in Alternatives A through C and identifies permitting, intake hydrogeology and brine discharge as the most important constraints.

Simo said the project is in phase 2a, the public-engagement and alternatives phase, and that the study is intended to present options rather than select a final site. "We are in phase 2a," he told the board, summarizing the work to identify alternatives, cost them, and list potential impacts and fatal flaws. He said the team has narrowed an initial 12 concept ideas to five refined alternatives that have been screened by environmental constraints, available outfalls and likely user partners.

Why it matters: the Central Coast's water system is drought-prone and heavily dependent on rainfall and imported water. A desalination option offers a drought-proof ocean source, but it raises environmental, permitting and cost questions that will shape whether and how the county proceeds.

What the study found: the five alternatives vary in scale and geography. Alternative A is a Cambria-area local delivery option that would serve Cambria and San Simeon but would require a new ocean outfall because the existing outfall is too small and lies inside a marine protected area. Alternative B (Estero Marine Terminal area) could also include Los Osos and requires significant pipeline. Alternative C (Morro Bay) is the largest option, using an existing outfall to deliver roughly 5,000'7,800 acre-feet and taking advantage of infrastructure exchanges. Alternatives D and E focus on South County users and the Nipomo Mesa refinery site respectively and do not include Cambria.

Costs and uncertainty: the team presented planning-level capital cost ranges that span roughly $200 million to $600 million across options, with large uncertainty at this level of design. Simo explained that ocean infrastructure (subsurface intakes and outfalls), treatment facilities and long-distance pipeline are the principal cost drivers and carry significant site-specific uncertainty.

Environmental and permitting issues: Simo emphasized state ocean and coastal rules requiring intakes to be subsurface where possible and described the study's spatial "pancake" screening overlaying habitat, easements and flood zones to find low-impact locations. He said development inside marine protected areas would likely require legislative changes, so the team seeks to place intakes outside MPAs and to use diffusers or commingled outfalls (mixing brine with other wastewater) where permitted.

Board and public reaction: Director Gray reminded the board of a 2006 Cambria desalination project that was denied by the Coastal Commission and pressed the consultants on lessons learned and how the new proposals would differ. "Is that an argument for a larger alternative C in the sense of spreading cost and inputs?" he asked; Simo acknowledged economies of scale but said governance, funding and right-of-way remain critical variables.

Public commenters raised reuse and alternatives. Ted Siegler suggested potable reuse and pointed out that agricultural demand may not be suited to desalinated water because of cost; Simo said potable-reuse projects are important but rely on wastewater availability, which can fall during droughts, whereas ocean desalination can supply from the ocean in dry conditions.

Next steps: staff said the draft public feasibility report will be made available in July and that the county will hold a public meeting with stakeholders; Mr. Green told the board a community survey is open through July 8 and a county-board briefing is planned for August. The study team also plans midterm steps (hydrology and soils studies, outfall dilution modeling, CEQA and permitting) and longer-term governance and financing analysis if the board and partners choose to advance a preferred alternative.

The study produced a range of technically feasible options but left open the key questions of who would pay for construction and operation, which environmental mitigations would be acceptable, and whether partners could commit to long-term offtake. The county's next decision point will be the Phase 2a conclusion and whether to move into Phase 2b to identify partners and pursue environmental review.