Groundwater agency outlines billion‑dollar options to slow seawater intrusion; board and public flag affordability

Royce Seagel, general manager of the Selenus Valley Basin Groundwater Sustainability Agency, briefed the board on April advisory‑committee work and presented several large infrastructure options to counter seawater intrusion in the basin.

Seagel opened the briefing by explaining the advisory committee’s charge: review staff‑developed project packages, consider combinations of elements, and recommend options to the board. He emphasized the board is the policymaking authority and the advisory committee’s role is to refine and recommend projects for board action.

The general manager said modeling shows a “no‑action” pathway and valleywide demand‑management scenarios (illustrative 30–50 percent cuts) would not, by themselves, prevent seawater intrusion from advancing by 2040. “If we stop pumping everywhere, we’re not going to be able to stop seawater intrusion from advancing by 2040,” Seagel said, noting that even an immediate halt to pumping would take many years to reverse intrusion.

Project options presented range widely in scale, yield and cost:

• Brackish Groundwater Restoration (BGR): Seagel described an extraction‑and‑injection design with roughly 20 extraction wells near the coast and about 21 inland injection wells. The presentation listed a capital cost near $951 million and an estimated treatment/injection capacity of about 46,000–47,000 acre‑feet per year. Unit costs were shown around $3,300 per acre‑foot; Seagel said the figure includes operations and maintenance and that desalting brackish water is energy‑intensive.

• Castroville/East‑Side canal and recharge concepts: A canal and recharge alternative—similar to historic Bulletin 52 concepts—was presented with a broad capital range ($200 million to $1.3 billion) and yields of roughly 5,000–27,000 acre‑feet per year. Unit costs were presented in a wide band ($1,700–$6,200 per acre‑foot) depending on scale and siting. Seagel flagged geology, water‑rights and habitat conservation plan obligations as complications for surface‑water diversion and recharge schemes.

• New Seawater Intrusion Project (NSIP) variant: A larger scheme linking existing infrastructure, additional piping and converted storage was shown with capital estimates from about $700 million to $1.4 billion; yields were presented in the 5,000–25,000 acre‑feet/year range and operating costs were lower in comparison to the highest‑cost alternatives.

Seagel said the BGR shows the strongest technical promise but warned that capital and ongoing costs are “really, really” high and may be unaffordable for local ratepayers without external funding. He noted the advisory committee includes members who are skeptical of affordability.

During a question‑and‑answer exchange, a board member asked where operations and maintenance costs appear in the materials; Seagel replied the unit‑cost figures include O&M and that some scenarios’ annual O&M can be high (one example discussed was on the order of tens of millions of dollars per year for larger options). He also said some options rely on surface water and therefore have reliability concerns tied to hydrology and storage.

Seagel summarized technical analysis from staff (identified in the briefing as “Gus”), who reviewed 1952–2024 precipitation and groundwater data. The analyst’s findings indicated multi‑decadal below‑average precipitation (about 6 percent below the long‑term average over a recent multi‑decadal period) and slow declines in groundwater elevations; Seagel said rainfall and runoff are important drivers of recharge and that, in many subareas, groundwater response is closely tied to precipitation rather than pumping alone.

Public comments focused on affordability and legal risk. Tom Versik, during public comment, urged the board to consider obtaining a contemporaneous legal opinion on whether state intervention could occur and whether a “good actor” exception applies in specific management areas. Versik also criticized certain no‑action assumptions in modeling and questioned how the county and basin processes will coordinate.

Seagel said the GSA must update its groundwater sustainability plan before the next due cycle and that two corrective items from the Department of Water Resources—interconnected surface‑water considerations and water quality—remain to be addressed. He told the board that a measured, scientifically grounded approach is needed to avoid unintended consequences seen in other basins.

The meeting included routine items: roll call, the pledge of allegiance, a consent calendar motion to approve minutes (the motion was seconded and at least one member voiced opposition during the vote; the transcript does not specify a final tally), and brief board remarks before adjournment.

Next steps Seagel outlined include further advisory‑committee deliberations in subsequent meetings, additional refinement of project combinations, and outreach to identify funding options; he reiterated that the board will need to consider affordability and who would bear costs if a 218 financing mechanism or other rate structure is pursued.