By Mark Shahinian
San Franciscans and their Bay Area neighbors have done something remarkable over the past quarter century: they've cut their water use by 30 percent. They've ripped out ornamental lawns, installed low-flow fixtures, and adapted their habits all while experiencing drought after drought. It's a genuine conservation success story.
So why is the agency that supplies their water—the San Francisco Public Utilities Commission—planning for a future in which demand goes up?
In a letter sent to SFPUC Commissioners this February, the Sierra Club argues that the draft 2025 Urban Water Management Plan—available for public review in March 2026—paints an unrealistically high picture of future water demand, with serious consequences for ratepayers and the Tuolumne River ecosystem.
The SFPUC has overestimated water demand by 45 to 50 percent on a 15-year horizon in every Urban Water Management Plan going back to 2000. Even the 2020 plan overshot 2025 water use by 13 percent just four years after it was issued. The new draft projections appear to continue this pattern, forecasting ever-increasing demand despite decades of evidence pointing the other way.
Using a statistical model built on the drought index, population data, and nearly fifty years of water use history, the Sierra Club projects 2050 demand at roughly 147 million gallons per day—compared to the 222 MGD the SFPUC and BAWSCA are projecting.
These inflated projections have real environmental consequences. The SFPUC and BAWSCA have used them to argue vigorously against the Bay Delta Plan—the state’s framework for restoring flows to Northern California rivers and one of the Sierra Club of California’s top priorities. Salmon populations in the Tuolumne River, which feeds the SFPUC’s water system, have declined precipitously. But the water agencies base their case against the Bay Delta Plan on inflated demand numbers and a design drought that by one analysis is likely to occur only once every 8,000 years.
The affordability picture is just as troubling. Inflated demand projections justify expensive capital projects; when that demand fails to materialize, the costs get spread over fewer gallons sold, driving up rates. This is already happening: the SFPUC’s proposed wholesale rate increases for the next two years jumped from 1 percent to more than 7 percent per year between May 2025 and January 2026. The SFPUC is projecting retail rate increases of more than 6.5 percent annually for seven years starting in 2027—meaning water rates will be at least 70 percent higher in eight years. Based on the agency’s own numbers, combined water and sewer bills will become unaffordable for typical San Francisco households within about a decade.
The Sierra Club is asking the SFPUC to create a working group to develop realistic demand scenarios with full data transparency, to reassess how supply needs are conceived in light of affordability and ecological concerns, and to budget for a collaborative review of its approach to the Bay Delta Plan. The environment and affordability are on the same side here—and that’s a rare and valuable thing. Read the full letter here.
If you have questions, contact the Sierra Club San Francisco Bay Chapter’s Water Committee.