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Zone 7 employee smiling at the camera while conducting a field test.

Groundwater

Sustainably managing our basin

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

Zone 7 actively monitors basin-wide groundwater levels and storage

Our main focus in 2021-2022 fiscal year has been meeting the statutory requirements to submit the updated Alternative GSP and the Sustainable Groundwater Management Annual Report for the Water Year 2021.  The half million-dollar grant received in March 2020 funded the Alternative GSP update and associated studies. We completed the Alternative GSP update on time and submitted to DWR by the January 1, 2022 deadline. Following the submittal of the Alternate GSP update, on March 31, we met the regulatory requirement by submitting the Sustainable Groundwater Management Annual Report, which contains essential components that satisfy the GSP regulations. As discussed in the Annual report, we continue to manage the groundwater basin sustainably while extracting 14,000 acre-feet of groundwater for much needed water supply during the current drought.  

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 completed a PFAS Potential Source Investigation (Jacobs Engineering, Inc. 2020) and a PFAS and Hexavalent Chromium Treatment Feasibility Study (Carollo, 2020). Continuing with PFAS management activities, during last year, the PFAS mobilization modeling study was conducted to analyze movement of known PFAS plumes under various pumping scenarios. We also started developing potential PFAS management strategies to manage the existing PFAS plumes in upper and lower aquifers.

Groundwater Protection Highlights

Zone 7 regularly samples and analyzes groundwater quality

Staying abreast of contaminants of emerging concern

PFAS (Per- and Polyfluoroalkyl Substances) are an emerging group of contaminants of concern and known as forever chemicals. USEPA as well as the State of California are developing maximum contaminant levels (MCLs) for PFAS compounds and are expected to set these MCLs in coming years.  A few PFAS compounds have been detected in several of the municipal supply wells in the Livermore Valley Groundwater Basin. In addition to 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 Quality Control Board to help investigate potential sources to better understand the source(s) of PFAS contamination and manage these contaminants. 

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. The objective is to protect the 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 within the groundwater basin such as manufacturing sites, petroleum storage, and solvents to keep track of groundwater contamination cleaned up by the responsible parties and prevent degradation of basin water quality. We tracked more than 62 contamination cases in our service area during 2021-2022 including case closures that have been cleaned up to state standards. 

Supporting the community through well owner voluntary monitoring program

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

Drought and Conservation

Watershed