Sierra Club Sues San Francisco's Water Agency, Saying It Overstates Future Demand by a Third

The Sierra Club has taken San Francisco's water department to court, arguing the agency is planning for far more water than the city and its suburban customers will actually use.

The petition, filed in San Francisco Superior Court in early October, asks a judge to order the San Francisco Public Utilities Commission to revise its Urban Water Management Plan, the forecast every large California water supplier must file with the state every five years. The SFPUC delivers water, much of it from the Tuolumne River and Hetch Hetchy Reservoir in Yosemite, to San Francisco and more than two dozen communities in San Mateo, Santa Clara and Alameda counties.

What the plan says, and what the Sierra Club says

The plan projects that demand from San Francisco residents will rise 17% by 2050 and demand from wholesale customers will rise 14%, for a combined total of about 222 million gallons a day, according to the San Francisco Chronicle. The Sierra Club says that overstates demand by roughly a third. Its own statistical model, published earlier this year, puts 2050 demand closer to 147 million gallons a day.

The group argues the agency has a long track record of overshooting. It says past plans overestimated demand by 45% to 50% over 15-year horizons, and that the 2020 plan overshot 2025 use by 13%. Water use across the SFPUC's service area has fallen by more than 30% over the past 25 years, the Sierra Club says.

The lawsuit also alleges the agency set aside lower estimates from its own finance staff in favor of higher numbers without explaining why, according to accounts of the filing.

Why it could matter for your bill

The Sierra Club's case isn't only about fish. It argues that high forecasts justify expensive new infrastructure and storage, and that when demand doesn't show up, fixed costs get spread over fewer gallons, pushing rates up. The group points to the SFPUC's own projections of retail rate increases of more than 6.5% a year for seven years starting in 2027.

The group says it is not trying to stop or cut water deliveries to the Bay Area; it wants the forecast redone. The suit lands as state regulators weigh an update to the Bay-Delta Plan that could limit how much water can be diverted from rivers like the Tuolumne. The SFPUC's response to the suit was not included in the reports reviewed for this story.