Annual Report 2023




acre-feet of potable water delivered to the four retailers for the homes and businesses of the Tri-Valley.


acre-feet of supplemental water made available locally for direct deliveries and recharge*

*The California State Department of Water Resources (DWR) makes this water available when it does not have storage capacity in the State Water Project system. This water is in addition to Zone 7’s normal State Water Project deliveries.


Zone 7 quickly transitioned treated source water supplies from using an average of 53% groundwater in the first half of the fiscal year to just 7% groundwater in the second half of the fiscal year once surface water supplies became available.

Sustainable Groundwater Management

In fiscal year 2022-2023, Zone 7 submitted the Sustainable Groundwater Management Annual Report for Water Year 2022 prior to the April 1, 2023 statutory deadline. The agency is currently awaiting DWR approval on the Alternative Groundwater Sustainability Plan submitted in 2021. We continue to manage the groundwater basin sustainably while extracting over 10,367 acre-feet of groundwater for much needed water supply during the drought.

Keeping our groundwater safe from PFAS

Per- and Polyfluoroalkyl substances (PFAS) are synthetic chemicals used in manufacturing a variety of consumer products such as packaging, non-stick surfaces, and fire-fighting foams. PFAS have been found in air, soil and water around the world, and have been found locally in our groundwater basin. In our ongoing effort to keep our water safe, Zone 7 has completed a variety of contamination management strategies.

  • PFAS Potential Source Investigation
    (Jacobs Engineering, Inc. 2020)
  • PFAS and Hexavalent Chromium Treatment Feasibility Study (Carollo, 2020)
  • PFAS Mobilization Modeling Study (2022) to analyze movement of known PFAS plumes under various pumping scenarios
  • Continued to develop potential PFAS management strategies to manage plumes in upper and lower aquifers
  • Tracked more than 62 contamination cases during 2022-2023 including case closures cleaned to state standards

Water Reliability Capital Project Updates

Sites Reservoir Project Progress

Zone 7 continued to invest in the Sites Reservoir Project, a proposed new off-stream reservoir project that could provide Zone 7 with a new water supply and upstream storage capacity.

  • Key planning effort progress
  • The Sites water rights application was publicly noticed by the State Water Resources Control Board, a major milestone in the water rights process.
  • The Water Infrastructure Finance and Innovation Act (WIFIA) loan application was submitted to the US Environmental Protection Agency.
  • The Final Environmental Impact Report/Environmental Impact Statement was submitted to the US Bureau of Reclamation for review and authorization to publish the document.


construction of Sites Reservoir is expected to begin


million acre-feet

of new storage capacity in Sites Reservoir


of eligible project costs could be covered by the WIFIA loan if approved

Los Vaqueros Reservoir Expansion Project

Zone 7 continued to invest in the Los Vaqueros Reservoir Expansion Project, which proposes to increase the Los Vaqueros Reservoir storage capacity from 160,000 acre-feet to 275,000 acre-feet and construct the Transfer-Bethany Pipeline, a regional intertie. The project could provide Zone 7 with new local upstream storage capacity and alternative conveyance.
  • Key planning effort progress
  • An executive director for the Los Vaqueros Reservoir Joint Powers Authority was hired to coordinate project activities.
  • The project was allocated $82 million by the US Bureau of Reclamation from the Bipartisan Infrastructure Law.
  • The US Environmental Protection Agency invited this project to apply for a Water Infrastructure Finance and Innovation Act loan, which could cover up to 49% of eligible project costs.




Construction begins on Transfer-Bethany Pipeline


Construction begins on Los Vaqueros Dam Expansion

$82 million

allocated to the Los Vaqueros expansion project by the US Bureau of Reclamation

115,000 acre-feet

of increased storage capacity proposed at Los Vaqueros expansion

Delta Conveyance Project

Zone 7 continued to invest in the Delta Conveyance Project, a proposed tunnel connecting two new intake facilities in the North Delta to the existing facilities in the South Delta. This project could provide Zone 7 with alternative conveyance and help increase the reliability of State Water Project supplies.
  • Key planning effort progress
  • The Draft Environmental Impact Report was released for public review and comment and several public hearings were held to receive verbal comments.
  • The Draft Environmental Impact Statement was released for public review and comment.
  • Several workshops were held to develop the framework for the Community Benefits Program to identify and implement projects that benefit the Delta community.


If the DCP was operational during the high rain events in January 2023, it could have moved 228,000 acre-feet of water into the San Luis Reservoir.

228,000 acre-feet of water

enough water

to supply:

over 2.3 million people for one year


nearly 800,000 households for one year

The theoretical DCP diversion of 228,000 acre-feet is about


of the total volume exported by the SWP in water year 2022. 

Community conservation efforts during historic droughts

The Zone 7 Board of Directors unanimously declared an end to the drought emergency and 15% mandatory conservation requirements on April 19, 2023. Working together with the community and retailers, the Agency exceeded the needed 15% conservation goal by 4% during some of the driest years on record for our area. We are grateful to the Tri-Valley community for their successful efforts to conserve our most precious resource during this time.

2.4 billion

gallons of potable water saved in FY23 relative to FY21

19% reduction

in potable water usage during the same period

Rebates help reach our conservation goals

In April of 2023, Zone 7 launched a pool cover rebate pilot program. The program offers up to $100 toward a cover for pools to help reduce evaporation. Additionally, Zone 7 continued to promote its High-Efficency Clothes Washer, Lawn Conversion, and Smart Irrigation Controller rebates in partnership with our retailers.


high-efficiency clothes washer rebates


water-efficient lawn conversion rebates


smart irrigation controller rebates


pool cover

Check out these reels to learn about our rebates

Conservation as a way of life

While the mandatory restrictions are no longer in place, Zone 7 encourages the Tri-Valley community to consider conservation a way of life. Changes in weather patterns and severe conditions mean having reliable water supply and plentiful reserves such as our local groundwater basin are critical for long-term sustainability of our region. 2023 was the first 100% State Water Project allocation since 2006, allowing Zone 7 to begin recharging the groundwater basin and helping it recover from the recent drought.


The Flood & Drought Cycle

A look at the past 20 years shows that periods of drought are followed by a flood season, with repeated periods of drought. This historical cycle teaches us the importance of long-term water storage planning.

Zone 7 Water Agency – Annual Report 2023

Zone 7 Water Agency – Annual Report 2023