SFPUC workshop outlines options to close a projected 20.7 MGD gap by 2035; staff highlights transfers, groundwater and conservation

At an extended workshop May 22, SFPUC staff presented a range of water-supply options to meet projected 2035 demand and framed a policy question for the commission about how to treat a potential 10 million gallon-per-day surplus in the city’s allocation.

Steve Ritchie, assistant general manager for water, told the commission that policy and regulatory changes combined with projected wholesale and retail demand could produce a total potential shortfall of about 20.7 million gallons per day by 2035. He reviewed the utility’s performance objectives (a system objective of 265,000,000 gallons per day with a wholesale supply assurance of 184,000,000 gallons per day and a retail allocation to San Francisco of 81,000,000 gallons per day) and said that regulatory requirements (in‑stream flows) account for a substantial portion of the projected shortfall.

Ritchie and staff described several supply options: a proposed 2,000,000 gallon-per-day transfer from the Modesto Irrigation District (characterized as dry‑year supply and described as an insurance policy against long droughts), a regional groundwater storage and recovery project (roughly 7,000,000 GPD of dry‑year supply), the San Francisco groundwater project, West- and East-side recycled-water projects, regional desalination, additional transfers from irrigation districts, and nonpotable programs. Staff emphasized reliability as a critical criterion when comparing options.

Staff also showed a matrix that applies five comparison categories — potable water quality, affordability, reliability, community interests and relative environmental impacts — across nine candidate projects, using qualitative scores (pluses, checks, blanks, minuses) and affordability bands (for example, less than $3,000 per acre-foot is ‘more favorable’). Commissioners debated whether to use a purely numeric scoring approach or the qualitative matrix; staff said the August retreat would be used for deeper prioritization and requested clearer definitions of the matrix criteria (for example, how to factor energy offsets and community support).

Commissioners and members of the public pressed staff on timing and priorities. One exchange summarized the policy choice facing the commission: whether to keep an anticipated 10 MGD of San Francisco’s allocation as insurance against drought, offer it to wholesale customers such as San Jose and Santa Clara, or otherwise allocate or sell it. Ritchie said the decision point depends on completion of the projects that create the surplus (groundwater, recycled water, conservation) and on negotiations with wholesale customers.

Peter Drechmeier of the Tuolumne River Trust urged the commission to explicitly include conservation in the matrix and noted that water use has dropped 45,000,000 GPD since the WISIP baseline; he provided a staff figure of $2,423 per acre-foot for the 2 MGD transfer (2018-dollar basis) and argued that conservation should be weighed alongside transfers. Staff responded that conservation will be included in future matrices and that they would present more detailed cost, energy and reliability math at the retreat.

Staff closed the workshop by committing to refine metrics, present additional quantitative detail and solicit public and citizen‑advisory feedback before the August off‑site workshop where commissioners will be asked to provide policy direction.