Water Supply Report Card

Measured with respect to the performance targets, progress toward a reliable water supply for California over the past 10 years is commendable. Improvements in urban water conservation and water use efficiency have contributed to increased local self-reliance and reduced demand for Delta water relative to baseline conditions. An expanding portfolio of alternative local water supply sources contributed to regional reliability and local self-reliance. Extended dry conditions dominated the decade, triggering emergency drought proclamations that impacted water allocations and mandated statewide water conservation. Managing the demand for water through urban conservation needs to continue to prepare for a hotter and dryer climate and to offset California’s population growth.

The following Water Supply report card was developed as part of the Delta Plan Review that used the established performance measures to rate progress in implementing the Delta Plan over the past ten year (2013-2023). Read the 2024 Delta Plan Review full report to learn about additional review findings and the recommended actions that will inform Delta management priorities in next five years.

The overall performance measure score is rated “VERY GOOD” (76%-100% of target met) as of 2023 based on metric:

  • Urban water use:  Urban water users reduced consumption by 20% between 2010 and 2020, using an average of 50 gallons less water per person. In 2015 and 2020, urban water use efficiency improved to 133-135 gallons per capita per day (GPCD), compared to 183 GPCD in 2010, implementing water conservation during periods of extended drought.

View more: Urban Water Use | Delta Stewardship Council (ca.gov)

The overall performance measure score is rated “VERY GOOD” (76%-100% of target met) as of 2023 based on metric:

  • Agricultural water use quantification: In the 2021 Agricultural Water Management Plan submissions, 93% of agricultural water suppliers that directly use State Water Project water reported water use efficiency, and 75% included accounting for Delta water use.

View more: Agricultural Water Planning | Delta Stewardship Council (ca.gov)

The overall performance measure score is rated “GOOD” (51%-75% of target met) as of 2023 based on the arithmetic mean of three metrics where urban water suppliers who met at least 75% of their projected beneficial use of:

  1. Recycled water projections: 27% in 2015 and 26% in 2020.
  2. Storm water-use projections: 100% in both years.
  3. Desalination projections: 60% in 2015 and 64% in 2020. Only urban water suppliers in the South Coast and Central Coast regions reported desalination data.

The combined average across all alternative sources was 62% in 2015 and 63% in 2020.

View more: Alternative Water Supply | Delta Stewardship Council (ca.gov)

The overall performance measure score is rated “VERY GOOD” (76%-100% of target met) as of 2023 based on an arithmetic mean of two metrics:

  1. Single Dry Year projected reliability: 95.2% in 2015, 93% in 2020.
  2. Multiple Dry Years (3 years) projected reliability: 91.4% in 2015, 91.75% in 2020.

In 2020, Over 90% of urban water suppliers in the state are meeting their dry-year reliability targets. This means that most agencies that depend on water from the Delta can reliably supply water with existing supplies and demand for one and multiple consecutive dry years.

View more: Water Supply Reliability | Delta Stewardship Council (ca.gov)

The overall performance measure score is “VERY GOOD” (76-100% of target met) as of 2023 based on an arithmetic mean of three performance metrics:

  1. Critically Dry Year Export Decrease: The critically dry year average annual exports between 2015 and 2023 were 1.92 million-acre feet (MAF). This is significantly lower than the yearly water baseline exports in critically dry years across 1975-2014 (3.9 MAF). Total annual exports in critically dry years 2015, 2021, and 2022 were 1.94 MAF, 1.65 MAF, and 2.18 MAF, respectively.
  2. Wet Year Exports: The wet year average annual exports between 2015 and 2023 were 5.7 MAF. This is higher than the baseline total exports in wet years across the period 1975-2014 (5.0 MAF). Total annual exports in wet years 2017, 2019, and 2023 were 6.46 MAF, 5.34 MAF, and 5.39 MAF, respectively.
  3. Exports Across All Years: Between 2015-2023, the average annual total Delta exports for all water year types were 4.87 MAF. This is lower than the baseline exports across 2000-2014 for all water year types (5.1 MAF). The fifteen-year average annual Delta export target to be achieved by 2030 is 4.85 MAF, representing a 5% decrease from historical exports.

View more: Water Exports | Delta Stewardship Council (ca.gov)