When the Palo Alto City Council publicly backed the Bay-Delta Plan in 2018, it was swimming against the political tide.

The plan, formally known as the San Francisco Bay/Sacramento-San Joaquin Delta Estuary plan, sets limits on how much water agencies can siphon from the three tributaries of the San Joaquin River. While it aims to protect salmon, steelhead and other river species, it has also attracted intense opposition and litigation from water districts that claim that the new restrictions will undermine the reliability of their water supply.

The council's decision to endorse the plan was lauded by local environmentalists, even as it runs counter to the recommendation from Utilities Department staff and against the warnings of its own water supplier, the San Francisco Public Utilities Commission. By the commission's projection, the combination of the Bay-Delta Plan and a drought would require the agencies it supplies to reduce their water by 50%.

This extreme scenario is among those contemplated in Palo Alto's new Urban Water Management Plan, which the council unanimously approved on Monday night. The document, which the city is required by state law to update every five years, includes a list of alternative supply sources as well as measures that the city would take to reduce water usage — from water audits and the distribution of low-flow showerheads to drought surcharges, a prohibition on sprinklers and a ban on car washing outside a car wash that uses recycled water.

The city already has some experience with droughts, having reduced its water usage by about 31% in 2015 through various measures, including limiting landscape irrigation to twice a week. But council member Greg Tanaka noted that some of the most extreme proposals in the new water plan go "above and beyond what we've ever done before."

"I think members of the public would be very surprised to see this kind of a dramatic cutback needed," Tanaka said.

In presenting the plan, Karla Dailey, senior resource planner in the Utilities Department, noted that the document does not commit the city to any particular restriction and that the council will have the option of adding additional methods for conserving water if needed.

"We take water demand management very seriously here in Palo Alto and given the dryness of the state that we're all witnessing firsthand, you will see an increase in outreach and education for the utility around demand management and the programs that we offer," Dailey said.

Some believe the scenario requiring 50% water reduction is highly unlikely. Peter Drekmeier, policy director at Tuolumne River Trust and former Palo Alto mayor, noted that the SFPUC's projection is based on an extremely conservative scenario known as a "design drought" — a hypothetical dry-spell stretching for eight-and-a-half years that the commission is using for planning purposes. Drekmeier noted in a letter that this scenario "shifts some of the rationing that would be required in the later years into the earlier years, making rationing appear much more severe than it needs to be."

He told the council Monday that the SFPUC's projections have been off by an average of 22% over the last 20 years.

"Demand projections are almost always inflated," Drekmeier said.

He requested that Palo Alto submit a letter to the SFPUC asking it to consider an alternative with a shorter design drought. The council agreed to the proposal by a 5-2 vote, with council members Alison Cormack and Tanaka dissenting.

The plan notes that given the city's forecasted water demand and the SFPUC's projections of water supply availability, the city "anticipates the need to implement water use reductions of nearly 50% in the first dry year post Bay Delta Plan implementation." At the same time, the existing agreement between the SFPUC and its wholesale partners requires the commission to discuss additional strategies for reducing water use before it implements water reductions exceeding 20%.

Nicole Sandkulla, CEO of the Bay Area Water Supply and Conservation Agency, which represents Palo Alto and 25 other agencies in purchasing water from the SFPUC, suggested that if the Bay-Delta Plan takes effect, there may be a period of time during a significant drought where the agencies may be subject to the severe restrictions while they're working to find other supply alternatives.

"That's a significant impact to our water supply and our water supply reliability," Sandkulla said of the Bay-Delta Plan.

Palo Alto, for its part, has a few other options to turn to if the SFPUC tightens the spigot. In 2019, the city entered into an agreement with the Valley Water, Santa Clara County's main water supplier, for construction of a water treatment facility for nonpotable water at the Regional Water Quality Control Plant. The deal includes a provision that gives Palo Alto the option of buying potable or nonpotable water from the water district.

Other options that the city can tap on during an extreme drought is its five wells — which are currently in "standby" mode — and groundwater, which the city has not pumped since 1991, according to the plan. While it is "not a planned future water supply source, groundwater is an available alternative that is evaluated and reviewed on a regular basis."

Despite the state's dry spell, Vice Mayor Pat Burt saw some signs of encouragement in the city's record of conservation: namely, its ability to use less water even as population continues to grow. According to the new report, Palo Alto's water sales decreased by 11% between 2010 and 2015, dropping from 11,375 acre feet per year to 10,177 acre feet (though usage did go up by 5% in the next five years, as the state emerged from the drought).

"In our community, there's often a misconception that we don't have adequate water allocation for population growth and that our water usage just keeps going up in proportion of population growth," Burt said. "The reverse has happened over a 30-year period pretty steadily."