A diversified water supply reduces demand on Delta water. In recent years, more than half of California’s urban water suppliers made progress toward this goal.
The Measure
Water suppliers that rely on water from the Delta should decrease their reliance on the Delta by increasing local water supplies including alternative sources of supply.
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Expectations
Ensuring the reliability of California’s water supply requires reducing reliance on water from the Delta. Water recycling, storm water capture, and water desalination can provide large amounts of new water to offset this reduction.
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Performance Metrics
- Percentage of water contractors or suppliers meeting their recycled water projections.
- Percentage of water contractors or suppliers meeting their storm water use projections.
- Percentage of water contractors or suppliers meeting their desalination projections.
Some regions do not show data. This may be due to data being unavailable in the Urban Water Management Plans. However, this does not mean that alternative sources are not being used by water suppliers in that region. If interested in viewing specific water suppliers, please search their urban water management plan from the Department of Water Resources Website: WUEdata - Water Use Efficiency Data (ca.gov).
Next Data Update: The next Urban Water Management Plan updates will be available in 2025 at the earliest. This performance measure will be updated soon after.
Urban water suppliers are required to submit plans to the Department of Water Resources (DWR) every five years showing their current sources of water supply, projections of future sources of water supply, and implementation of utilizing alternative water sources. Using alternative sources of local water supply is expected to increase regional water reliability and decrease reliance on the Delta. Recycled water, storm water capture, and desalination are all sources of alternative water supply.
Storm water runoff is a potentially large and currently underutilized source of water. California’s Global Warming Solutions Act of 2006 (AB 32) found that up to 333,000 acre-feet of storm water could be captured on an annual average basis for reuse in Southern California alone. That is enough to support more than 3 million Californians' residential water use for a year (Based on an 85 gallon per day California average in 2016).
Recycled water could dramatically improve the efficacy of some water systems. For example, in 2018, the Dublin San Ramon Services District which serves 173,000 customers was able to supply 20% of its water from recycled sources.
Seawater desalination technology, though expensive, is a useful water supply option already being used by some coastal cities such as Santa Barbara. Where locally appropriate some inland locations use desalination to treat brackish groundwater.
A diverse portfolio of alternative local water sources contributes to a more reliable water supply for California.
Each chapter of the Delta plan includes strategies to achieve the goals of the plan. These strategies are general guidance on achieving the objective laid out in the plan and in the Delta Reform Act of 2009. Associated with these strategies are recommendations. The recommendations describe more specific and implementable actions to support the achievement of Delta Plan strategies. Strategies and recommendations may also have associated performance measures. Delta Plan performance measures track progress in achieving desired outcomes for the Delta Plan. Below are the strategies and recommendations associated with this performance measure.
Delta Plan Strategy
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Increase water conservation and expand local and regional supplies
Delta Plan Recommendations
- Implement Water Efficiency and Water Management Planning Laws
- Require State Water Project Contractors to Implement Water Efficiency and Water Management Laws
- Ensure Compliance with Reasonable and Beneficial Use
- Expand Water Supply Reliability
- Develop Water Supply Reliability Guidelines
- Revise State Grant and Loan Priorities
- Demonstrate State Leadership
Metric
- Percentage of water contractors or urban water suppliers meeting their recycled water projections. This will be evaluated at least every five years as UWMPs are updated.
- Percentage of water contractors or urban water suppliers meeting their storm water-use projections. This will be evaluated at least every five years as UWMPs are updated.
- Percentage of water contractors or urban water suppliers meeting their desalination projections. This will be evaluated at least every five years as UWMPs are updated.
Baseline
- Each five-year UWMP update includes projections of future water supply sources in five-year increments.
Target
- Suppliers meet at least 75 percent of their projected beneficial use of recycled water, storm water, and desalinated groundwater or ocean water, established in their previous UWMP. Achievement of target to be met every five years as set by UWMP updates.
Methods
The data is from UWMP table 6-5. The list was was shortened to include only suppliers that included a non-zero and non-null total 2015 projected or actual recycled water supply. For those suppliers a 2015 projected recycled water was summed then actual 2015 recycled water was summed. Where suppliers' recycled water was greater than or equal to their total projection they were considered as having met their projection even if the beneficial use for the recycled water was different than they projected. Suppliers who did not project recycled water supply for 2015 but had actual water supply in 2015 were considered having met projections for the purposes of this measure.
The suppliers were aggregated by hydraulic region. Then, a percentage of suppliers meeting their projections was calculated. The few suppliers without a specified hydraulic region were calculated into the statewide total.
The same analysis was performed for projections of stormwater and desalination. Stormwater is not a specified category so Santa Monica is the only UWMP we found that projected stormwater supply. Other suppliers may have stormwater supply that they describe in a different supply category (e.g. Other).
Each supplier's total 2015 projection was summed across all three alternative water sources. Then that projection was multiplied by 0.75. Then we compared the sum of actual 2015 alternative water supplies to 75% of their projections. Those that exceeded it were considered having met the target according to the performance measure .