Are SF and SoCal Prepared for Droughts and Climate Change?

Scientists and conservation groups including NRDC have been warning for years that farms and cities in California need to plan to divert less water from the Bay-Delta watershed, and the 2009 enactment of the Delta Reform Act established that it is State policy to reduce reliance on water supplies from the Bay-Delta through investments in local and regional water supplies like water recycling (Cal. Water Code § 85021). The current drought is an unwelcome reminder that we are not prepared for drought, leading to the State Water Board ordering curtailments of some water diversions, ongoing violations of water quality standards in the Delta, DWR shutting down hydropower generation at California’s second largest reservoir because water levels are so low, and reservoir operations likely to kill nearly all of California’s endangered Chinook salmon in the Sacramento River this summer.

2021 also happens to be the year when urban water suppliers in California are required to prepare and submit their Urban Water Management Plans (“Plans”), which project the agencies’ respective water supplies and demands over the course of the next 25 years (the Plans must be updated every five years). The Plans prepared by the Metropolitan Water District ("MWD") and the San Francisco Public Utilities Commission ("SFPUC") affect water supply for millions of Californians, in addition to affecting how much water is left in California’s rivers for salmon and the state’s embattled ecosystems. MWD is the largest water agency in California, as the wholesaler supplying water to over 19 million people across the greater Los Angeles, Orange County, and San Diego regions. SFPUC, for its part, supplies water to nearly 900,000 retail customers (mostly in the City and County of San Francisco) and to over 1.86 million wholesale customers in the San Francisco Bay Area. Both MWD and SFPUC import water from the Bay Delta watershed, so their water diversions affect the health of the Central Valley’s beleaguered salmon runs and other native fish and wildlife; SFPUC diverts unsustainable amounts of water from the Tuolumne River, while MWD is the largest State Water Project contractor, which exports water from the Delta (and also imports water from the Colorado River).

NRDC compared MWD and SFPUC’s Urban Water Management Plans to understand how each agency is planning for the future. We analyzed demand projections (both overall demand and net demand on water agencies), projected diversions from the Bay-Delta, recycled water supplies, local supplies, and whether the agencies project they will have adequate water supplies to meet demand in the coming decades.

While there may still be folks who believe the myth that Southern California wastes water, it’s clear from this analysis that SFPUC consistently lags behind MWD in almost every metric. NRDC provided comments on the draft Plans for both agencies, and our comments were critical of some of the assumptions and estimates in both agencies' Plans (see NRDC's comments on MWD's draft Plan here and our comments on SFPUC's draft Plan here). We believe that both agencies have more to do to secure a sustainable water future, but Southern California appears to be a generation ahead of Northern California when it comes to progressive water management. Our results are summarized below.

Growth in Demand for Water*
 

Both agencies anticipate increased demand for water, but the Bay Area anticipates much higher rates of growth, which could worsen the imbalance between water supply and demand. Demand in MWD’s service area is projected to increase 5.89% between 2025 and 2045, from 3,767,000 acre-feet to 3,989,000 acre-feet. SFPUC’s retail area demand during that timeframe is projected to increase nearly three times as much—14%—from 79,248.31 acre-feet to 90,345.32 acre-feet.

Demand on MWD vs. Demand on SFPUC
 

Both agencies also serve as wholesale water agencies, and SFPUC and MWD are not the only source of water supply for the retail water agencies that directly serve residents. However, while agencies in Southern California are planning to reduce demand for water that is purchased from MWD, water agencies in Northern California are planning to increase water purchases from SFPUC. Between 2020 and 2045, the demand on MWD is projected to decrease by 13.57%, from 1,442,781 acre-feet to 1,247,000 acre-feet. This means that Southern California plans to meet more of their demand for water through increased water use efficiency, local water supplies and other sources. SFPUC, on the other hand, projects that there will be a 19.05% increase in demand on the water agency, from 222,612.65 acre-feet in 2020 to 264,846.47 acre-feet in 2045.

Diversions from the Bay-Delta*
 

For the first time that we’re aware of, MWD is planning for slightly less imported water from the Bay-Delta; their Plan projects that MWD’s reliance on Bay-Delta diversions will decrease to 633,000 acre-feet (22.96% of total water supply sources) in 2045, a net reduction of 14,000 acre-feet.

In contrast, SFPUC plans for increased water diversions from the Tuolumne River; in 2025, SFPUC’s Regional Water Supply (i.e., water from the Tuolumne River) is projected to supply 95.05% of total retail water supply (75,325.13 acre-feet). In 2045, the Regional Water Supply is projected to supply 91.44% of water for the retail area (82,611.04 acre-feet). While reliance on the Regional Water Supply as a percent of total retail water supply decreases, the actual volume of water supplied by the Tuolumne River is projected to increase by 7,285.91 acre-feet between 2025 and 2045.

In reality, both SFPUC and MWD will need to plan for far less water from the Bay-Delta watershed than what is assumed in their Plans. Recent modeling by MWD indicates that much of the region can adapt to significantly greater reductions in water supplies from the Bay-Delta, whereas SFPUC doesn’t seem to have a plan for complying with the reduced water diversions required under the 2018 Bay-Delta Water Quality Control Plan.

Recycled Water*
 

Water recycling provides a drought-resistant source of new water supplies, as well as creating good paying local jobs in the community. In Southern California, MWD estimates that water recycling will increase 265,000 acre-feet between 2020 and 2045, from 441,000 acre-feet to 706,000 acre-feet. And as we noted in our comments on MWD’s draft Plan, additional water recycling projects could increase supplies by several hundred thousand acre-feet per year.

In contrast, in Northern California SFPUC’s retail recycled water supplies are projected to increase by a mere 2,690.18 acre-feet, from 112.09 acre-feet in 2020 to 2,802.27 acre-feet in 2045. Because SFPUC’s Plan did not provide information on water recycling in the larger geographic area where they are a water wholesaler, this graphic only shows water recycling in the retail service area. But while there are other efforts to increase water recycling in the wholesale service area, including Valley Water’s Countywide Water Reuse Master Plan (which anticipates increasing potable water recycling to 24,000 acre-feet per year by 2040 and a total of 33,000 acre-feet per year of nonpotable water recycling), these efforts also seem to lag hundreds of thousands of acre-feet behind Southern California’s plans.

Local Water Supplies*
 

Southern California has invested in local and regional water supply projects for many years, and is planning for increased investments in water recycling, stormwater capture, and similar projects moving forward. Local water supplies are expected to make up 55.88% of MWD’s total supplies in 2025 (2,105,000 acre-feet). The percent of total MWD supplies from local sources is projected to increase to 58.77% by 2045 (2,345,000 acre-feet).

In 2025, SFPUC is projected to source 3,923.18 acre-feet of local water supplies, accounting for 4.95% of the total retail water supply. Local supplies are expected to make up 8.56% of SFPUC’s total retail supply (7,734.28 acre-feet) by 2045.

Water Supplies vs. Demand

MWD projects that they will maintain a surplus of water supplies between 2025 and 2045 (i.e., they will have more than enough supplies to meet projected demand). MWD’s surplus ranges between a minimum of 1,228,000 acre-feet of water (2025) and a maximum of 1,287,000 acre-feet of water (2035).

In contrast, if the updated Bay-Delta Water Quality Control Plan is implemented (the State Water Board adopted updated standards in 2018 that require increased instream flows in the Tuolumne River to protect salmon and other fish and wildlife), SFPUC projects annual shortages of water supplies, increasing in volume 48.04% from 71,626.1 acre-feet in 2025 to 106,038.1 acre-feet in 2045.

Conclusion

MWD and SFPUC are two of the State’s largest water agencies, and their Plans show that the Bay Area water agency has fallen behind its counterpart in Southern California when it comes to sustainable water planning and reducing reliance on the Bay-Delta. Over the next 25 years, MWD has identified significant investments in local and regional sustainable water projects like water recycling, while SFPUC plans to increase their diversions from the fragile Bay-Delta ecosystem with very minimal increases in local and regional water supplies. Nevertheless, both agencies have opportunities expand local and regional supplies, increase water use efficiency, and reduce demand for imported water. Moreover, both agencies are hiring or have hired new general managers, which presents new opportunities for change.

Water agencies across California need to realize and plan for the reality of significantly reduced water diversions from the Bay-Delta. SFPUC’s and MWD’s Plans show that there’s more work to be done by two of the state’s largest urban agencies, and that Northern California has a lot of work to catch up to Southern California. As the current drought demonstrates, there’s no time—or water—to waste.

*Wholesale breakdown not available for SFPUC

About the Authors

Doug Obegi

Director, California River Restoration, Water Division, Nature Program

Ashley Cooper

Program Assistant, Water & Wildlife, Nature Program

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