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Groundwater

Sustainably managing our basin

Our groundwater basin is a valuable resource for the Tri-Valley.  As the designated Groundwater Sustainability Agency (GSA), recognized in the Sustainable Groundwater Management Act (SGMA), Zone 7 proactively manages the groundwater basin to ensure it remains a sustainable source of water for future generations. It is a requirement of the state that we prepare and implement a Groundwater Sustainability Plan (GSP).  Because the groundwater basin has been monitored since the early 1960s and sustainably managed for over 45 years – since 1974, Zone 7 was allowed by the Department of Water Resources (DWR) to submit an Alternative GSP in 2016. This was one of only nine Alternative GSPs that were accepted by DWR across the state, a big win for the Tri-Valley and a testament to proactive and sustainable groundwater management that is central to the Zone 7’s mission and history.

Our focus in 2020-2021 fiscal year has been implementation of the half million-dollar grant received in March 2020 to fund the 2021 update to the 2016 Alternative GSP, specifically, expanding our knowledge of the fringe and upland basins – the unincorporated areas, hills, and recharge areas on the outlying areas of the basin and how they relate to the main basin. This includes updated cross-sections of the groundwater basin that extend out into the fringe and upland that have been generated during the grant project. Another aspect of the Alternative GSP update was a study that was conducted to identify groundwater dependent ecosystems. This new data increases our understanding of the basin and promotes better management for the future. This updated Alternative GSP was submitted to DWR for review.

Significant Achievements in Groundwater

$500,000 in grant funding used to complete the Alternative GSP Update and associated studies

240,000 acre-feet of total groundwater storage maintained

14,344 acre-feet of water pumped from our groundwater wells

Salt and Nutrient Management Plan

Our groundwater resources team continues to manage basin water quality, including salts and nutrients, to protect the long-term water quality of the Main Basin. With the enactment of Sustainable Groundwater Management Act in 2014, we continue managing groundwater quality as one of the six sustainable management criteria by implementing the Alternative GSP.

Proactive PFAS management

In our ongoing effort to keep our water safe, Zone 7 implemented proactive PFAs management strategies including conducting a PFAS Potential Source Investigation (Jacobs Engineering, Inc. 2020) and a PFAS and Hexavalent Chromium Treatment Feasibility Study (Carollo, 2020).

Groundwater Protection Highlights

Zone 7 keeps your water clean, safe, and high quality

Staying abreast of contaminants of emerging concern

PFAS (Per- and Polyfluoroalkyl Substances) are an emerging group of contaminants of concern and regulations are changing. A few PFAS compounds have been detected in several of the municipal supply wells in the Livermore Valley Groundwater Basin. In addition to required quarterly sampling of supply wells, Zone 7 has been analyzing monitoring well and surface water samples for PFAS compounds. Staff is working closely with the Regional Water Board to help identify potential sources for cleanup to ensure all water is safe to drink before delivery.

Issuing and inspecting well permits

Zone 7 issues permits for any drilling or excavation deeper than 10 feet below ground surface and destruction of existing wells in our service area. Inspections of the drilling sites are also performed after issuing permits. This permitting and inspection allow staff to ensure that wells and boreholes are properly constructed, and abandoned boreholes are properly backfilled. This also allows for the protection of the groundwater basin water quality by preventing migration of contaminants through improperly constructed or abandoned wells acting as conduits for groundwater contamination.

Vigilant monitoring through toxic site surveillance

This program coordinates with other County and State agencies to monitor information on ongoing and historic contamination sites such as manufacturing sites, petroleum storage, and solvents to ensure groundwater contamination is cleaned up by the responsible parties. We tracked more than 50 contamination cases in our service area during 2020-2021 including case closures that have been cleaned up to state standards.

Supporting the community through well owner voluntary monitoring program

Zone 7 supports our network of well owners across the basin by providing staff assistance to sample and analyze for general minerals and metals. The lab results and interpretations are shared with well owners.

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Drought and Conservation

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Watershed