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Zone 7 and Groundwater

In the Sustainable Groundwater Management Act (SGMA), the California Department Water Resources (DWR) designated the Zone 7 Water Agency as the exclusive Groundwater Sustainability Agency (GSA) for groundwater basins within its boundaries. Zone 7’s service area overlies almost all of the Livermore Valley Groundwater Basin (DWR 2-10), all of the Sunol Valley Groundwater Basin (DWR 2-11), and a small section of the San Joaquin Valley Groundwater Basin (DWR 5-22.15).

GW Basin Image 

The Sunol Valley Groundwater Basin is designated as very low priority and is therefore not subject to SGMA. In the San Joaquin Valley Basin, Zone 7 has executed a MOU with the San Luis & Delta-Mendota Water Authority (SLDMWA) to support SGMA compliance, and a GSP for that basin is anticipated in January 2022.

Zone 7 has been managing the Livermore Valley Groundwater Basin since the 1960s and uses it for water storage and municipal supply. It is an inland alluvial basin underlying the Cities of Dublin, Livermore, and Pleasanton, California. For purposes of groundwater management, the basin has been divided into three management areas based on varying geologic, hydrogeologic, and groundwater conditions:

  • Main Basin - produces water from a thick alluvial sequence that contains the highest yielding aquifers, best quality groundwater, and the major municipal wells.
  • Fringe Basins - characterized by relatively thin alluvium overlying the Livermore Formation that has limited groundwater storage, low well yield, and poor water quality.
  • Upland Areas - underlain by low-yielding formations with relatively few wells.

For a detailed description of the Livermore Valley Groundwater Basin including cross sections and maps, see Section 2 of the Alternative Groundwater Sustainability Plan.

Groundwater Sustainability

Zone 7 has been sustainably managing the Livermore Valley Groundwater Basin since the 1960s.

Basin graph 1900 2020

Groundwater from the basin is used for agricultural, municipal, industrial, domestic and undifferentiated supply purposes. Supply wells are distributed throughout the basin with the major municipal wells in the Main Basin. Agricultural pumping has decreased significantly since 1974 when imported surface water became available to many irrigation customers. Municipal wells now account for most of the pumping. Municipal pumping by retailers is contractually limited to a groundwater pumping quota (GPQ). Zone 7 pumps only groundwater that has been stored in the basin as part of its artificial recharge program. Zone 7 pumping is for municipal purposes, salt management, demand peaks, and any shortage or interruption in its surface water supply or treatment.

To keep track of basin conditions, Zone 7 has the following monitors programs to help the following:

  • Groundwater elevations
  • Groundwater quality including salt, nitrate, boron, chromium, and PFAS
  • Land surface elevations,
  • Streams Program – streamflow
  • Climatological Program – rainfall and evaporation
  • Land Use – water usage and source of water (recycled water, groundwater, municipal)
  • Wastewater and Recycled Water Use
  • Mining Area Activities

Zone 7 uses the results of these monitoring programs to perform the following management actions:

  • Importing, artificially recharging, and banking surface water to meet future demands,
  • Implementing a conjunctive use program that maximizes use of the storage capacity of the groundwater basin, including long-term implementation of the Chain of Lakes Program,
  • Managing groundwater pumping for sustainability,
  • Maintaining sustainable long-term groundwater storage volumes with natural and imported supplies,
  • Promoting sound recycled water use, and
  • Identifying and planning for future supply needs and demand impacts.
  • Groundwater quality (PFAS, Toxics, Salt Management, Nutrient Management Plans)

Groundwater Management/Sustainability Plans

In 2005, the Agency adopted a Groundwater Management Plan (GWMP), which documented ongoing policies and programs for managing groundwater to support existing and beneficial uses in the valley. This was amended in June 2015 with the adoption of the Nutrient Management Plan. Zone 7 also prepares annual reports of the groundwater basin that summarizes the basin conditions over the water year (from October to September).

Through these and other programs, Zone 7 has sustainably managed the basin to avoid undesirable results for at least 10 years since the 2005 adoption of the GWMP. The historical groundwater data shows that the basin has been operated sustainably for about half a century including three major droughts. Most of the data sets discussed in this Alternative Plan date back to 1974 allowing a comprehensive, long-term assessment of Zone 7’s basin management.

The Sustainable Groundwater Management Act (SGMA) is a combination of three bills signed by the California Governor Jerry Brown in 2014: Assembly Bill (AB) 1739, Senate Bill (SB) 1168, and SB 1319. This landmark legislation recognizes that groundwater is most effectively managed at the local level and provides local agencies with a framework and timeline to achieve or maintain groundwater sustainability.

In SGMA, sustainable groundwater management is defined as management of groundwater supplies in a manner that can be maintained in planning and implementation phases without causing “Undesirable Results”. Undesirable Results include the “significant and unreasonable” chronic lowering of groundwater levels, reduction of groundwater storage, seawater intrusion, degraded water quality, land subsidence, and interconnected surface waters.

Alternative Groundwater Sustainability Plan

Under the Sustainable Groundwater Management Act (SGMA), Zone 7 was designated as the exclusive Groundwater Sustainability Agency (GSA) for groundwater basins within its service area. As the GSA, Zone 7 was required to prepare either a Groundwater Sustainability Plan (GSP) or an Alternative Plan. Such an Alternative Plan must cover the entire groundwater basin, be functionally equivalent to a GSP, and demonstrate that the entire basin has been operating within its sustainable yield for at least 10 years. Given the ongoing sustainable management of the Livermore Valley Groundwater Basin over forty years, Zone 7 submitted an Alternative Plan in 2016 for compliance with SGMA and GSP regulations. Alt GSP are required to be updated every five years.

2022 Update to the Alternative GSP

DWR approved the Alternative GSP in 2019. In their approval DWR recommended that Zone 7 extend the criteria of minimum thresholds developed for the Main Basin (e.g. historic low water levels) into the Fringe and Upland portions of the Basin (see Figure 1). This will require extending geologic cross sections and modifying and extending the existing model. In addition, Zone 7 received two comment letters from The Nature Conservancy on the Alternative GSP, which recommended further evaluation of Groundwater Dependent Ecosystems. At the time of Alternative GSP preparation, limited information was available on wetlands and vegetation associated with groundwater. Since then, DWR has provided the Natural Communities Commonly Associated with Groundwater (NCCAG) mapping, which is a useful tool to help in identifying potential groundwater dependent ecosystems.

In November 2019 Staff submitted a detailed grant proposal for a DWR-administered Proposition 68 grant for $666,500, of which $499,875 was to be reimbursed by the grant. DWR approved the grant proposal in April 2020 and in May entered into agreement with Zone 7 for the project. The DWR-approved workplan addresses the DWR recommended actions for the Alternative GSP and the comment letters recommending additional analysis of GDEs.

On June 17, 2020, Zone 7 staff presented a summary of the grant project at a public Zone 7 Board meeting (agenda and presentation materials). During that meeting the Board also authorized a contract with a highly qualified consultant (EKI Consultants, Inc.) to assist staff on some portions of the project.

Zone 7 has developed a Stakeholder Communication and Engagement Plan - to support stakeholder outreach during the 2022 Alternative GSP process. For more information and to stay engaged, please check the Zone 7 website (http://www.zone7water.com) or sign up for Zone 7’s E-Newsletter at: https://www.zone7water.com/news/enewsletter-signups. Please email groundwater@zone7water.com if you would like more information regarding Zone 7’s activities related to the Sustainable Groundwater Management Act.

Grant workplan is available HERE