- The Sierra Club alleges San Francisco’s water utility has repeatedly overstated future water demand.
- The lawsuit claims some forecasts have exceeded actual demand by 40% to 50%.
- Water use in communities served by the utility has fallen more than 30% over 25 years, according to the Sierra Club.
- The environmental group says inflated forecasts affect river ecosystems and customer costs.
- San Francisco’s water and sewer rates are increasing by approximately 12.5% annually over two years.
Monday, October 12, 2026 — A legal fight over how much water San Francisco needs could affect rivers, fish, and millions of Bay Area water customers.
On October 6, 2026, the Sierra Club announced
that it had filed a petition in San Francisco Superior Court challenging the San Francisco Public Utilities Commission’s forecasts of future water demand.
The environmental organization alleges the utility has repeatedly predicted that customers would need far more water than they actually used. It also claims the agency has failed to explain why its internal financial forecasts differ from the water demand estimates presented to the public.
At the center of the dispute is a basic question: How much water will San Francisco and its surrounding communities really need in the coming decades?
Water Use Has Fallen, but Forecasts Keep Rising.
According to the Sierra Club, water consumption in San Francisco and other communities served by the utility has declined by more than 30% over the past 25 years.
Despite that decline, the organization says the utility has continued to forecast increasing demand.
The Sierra Club alleges that some past projections overstated actual water demand by 40% to 50%.
The organization also claims internal emails show utility staff encouraging outside consultants to change their assumptions in ways that would produce higher estimates of future water needs.
These allegations are central to the court challenge. The information provided does not establish that a court has ruled on their accuracy.
Two Different Forecasts Raise Questions.
One of the more unusual allegations involves the utility’s use of two different sets of water demand projections.
According to the Sierra Club, the agency’s financial staff developed forecasts suggesting water sales would remain relatively flat.
Meanwhile, other departments used projections showing greater future demand.
The environmental group argues that the agency did not adequately explain these differences in its public planning documents.
John Bauters, chair of the Sierra Club’s San Francisco Bay Chapter, criticized the practice.
“The law asks the SFPUC to show its work and tell the public the truth about what its own staff found. Instead, the agency published one demand projection for the money and a different one for the environment. Ratepayers pay the price difference while the Bay-Delta ecosystem pays the environmental difference.”
California law requires urban water suppliers to prepare water management plans every five years. These plans include estimates of how much water customers will need in the future.
Those estimates help guide decisions about water supplies, infrastructure investments, and long-term planning.
The Sierra Club contends that inaccurate forecasts can lead to decisions based on water needs that may never materialize.
Why the Dispute Matters for Rivers and Fish.
The lawsuit also involves a long-running disagreement over environmental protections for the San Francisco Bay and Sacramento-San Joaquin River Delta.
The Sierra Club argues that overstating future water demand can help justify diverting more water from rivers rather than leaving it available for fish and other wildlife.
The organization specifically criticizes the utility’s opposition to the Bay-Delta Plan, an environmental effort intended to improve water conditions for aquatic ecosystems.
According to the Sierra Club, inflated demand estimates have played a key role in the utility’s opposition to that plan.
The organization maintains that more accurate forecasts would provide a better foundation for decisions involving both water deliveries and environmental protection.
Customers Face Higher Water Bills.
The dispute comes as San Francisco residents face substantial increases in water and sewer bills.
The San Francisco Public Utilities Commission approved new water and sewer rates following a public hearing on April 28, 2026.
According to the utility’s published information, the average residential household faces the following increases:
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Fiscal year 2027: An additional $21 per month, approximately 12.6%.
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Fiscal year 2028: A further $23 per month, approximately 12.5%.
The new rate schedule took effect July 1, 2026.
The Sierra Club has criticized the agency’s spending decisions, including construction of a new water department headquarters that the organization says costs $400 million.
However, the utility offers a different explanation for the rate increases.
The commission says its water and sewer systems require extensive maintenance and upgrades. Some parts of the water system are nearly 100 years old, while the oldest sewer infrastructure dates back to California’s Gold Rush.
The agency says rate increases are necessary to replace aging pipes, prevent system failures, improve earthquake safety, meet environmental requirements, and maintain reliable service.
It also emphasizes that it operates as a nonprofit public utility, with services funded primarily through customer rates rather than taxes.
The commission says independent rate analysts recommended the increases based on operating expenses and infrastructure needs.
The utility’s explanation for the rate increases does not directly address the Sierra Club’s allegations concerning conflicting water demand forecasts.
What the Sierra Club Wants the Court to Do.
The Sierra Club is not asking the court to stop water deliveries or reduce the amount of water available to San Francisco customers.
Instead, the organization wants a judge to require the utility to revise its water management plan.
The requested changes include using demand forecasts supported by actual water use and clearly explaining why the agency’s different projections do not agree.
The Sierra Club says it raised these concerns through written and oral communications before the commission adopted its plan.
According to the organization, the commission did not adequately address those concerns.
The environmental group also argues that inflated water demand forecasts are not unique to San Francisco, describing the problem as one affecting other California urban water agencies.
The petition places the utility’s planning practices before the Superior Court, where the allegations and requested changes can be examined.
The sources provided do not include a formal response from the San Francisco Public Utilities Commission to the October 2026 court petition.
Editorial note: The lawsuit’s claims are attributed to the Sierra Club throughout. The utility’s published rate information provides its explanation for increased customer charges but is not presented as a response to the lawsuit.
