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Groundwater Plays an Important Role in Regional Water Supply

The GSP Aims to Protect a Vital Water Resource

Three water sources—surface water, recycled waterr and groundwater—serve all of the needs within the San Luis Obispo Valley Basin (SLO Basin). SGMA, the Sustainable Groundwater Management Act, signals the first time in California’s history that groundwater will be formally managed. 

Groundwater is the water found underground in the cracks and spaces in soil, sand and rock. It is stored in and moves slowly through geologic formations of soil, sand and rocks called aquifers. 

During a normal year, nearly 40 percent of California’s agricultural and urban water demand is met by the use of groundwater. For the Southern Central Coast Region where the San Luis Obispo Valley Groundwater Basin (SLO Basin) is located, approximately 80 percent of the total water supply is met by groundwater. This has resulted in conditions of critical overdraft with rapidly declining groundwater levels in some groundwater basins. Groundwater use also increases during drought conditions.


As required by SGMA, local agencies (the City and County of San Luis Obispo), in coordination with several local water purveyors (Edna Valley Growers Mutual Company, Edna Ranch Mutual Water Company, Varian Ranch Mutual Water Company and Golden State Water Company), are developing a Groundwater Sustainability Plan (GSP) to better manage this important water resource for the SLO Basin while meeting the requirements of SGMA

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SGMA: The Sustainable Groundwater Management Act 

In an effort to ensure the sustainable use of California’s groundwater and a water secure future for the State, SGMA was signed into law in 2014. 


SGMA is a State law that requires local governments and water agencies that overlie high and medium priority basins to form Groundwater Sustainability Agencies (GSAs) for the purpose of sustainably managing the groundwater basins. Locally, the SLO Basin has been identified as a high priority basin by the State. Therefore, in order to meet SGMA requirements, the County of San Luis Obispo (County) and the City of San Luis Obispo (City) each formed a Groundwater Sustainability Agency (GSA). These two GSAs are the governmental entities that are tasked with developing and implementing the SLO Basin's GSP. 


Although the GSAs were formed by the two local public agencies (the City and County of San Luis Obispo), representatives of the Golden State Water Company, Edna Ranch Mutual Water Company, Varian Ranch Mutual Water Company and Edna Valley Growers Mutual Water Company were engaged in developing a governance structure.  


In addition to the formation of the two GSAs, a Groundwater Sustainability Commission (GSC), an advisory body to the GSAs, was established through a Memorandum of Agreement (MOA) between the GSAs and the above participating parties, and the terms under which the City GSA and County GSA will jointly develop a single GSP in coordination with the GSC.

Learn more about SGMA

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5 Steps to Sustainable Groundwater in the SLO Basin

The GSP will be developed in phases through the end of 2021 to meet the required completion deadline of January 31, 2022. There will be ample opportunity for the public to participate in the plan development process, including participation in quarterly public GSC meetings and/or interactive workshops, and by reviewing and commenting on each GSP chapter/section as it is made available. For detail on how to get involved in each phase of the project, visit the Get Involved page.



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Know Your Representative in the GSP Process


Key Terms

Groundwater Sustainability Plan (GSP) — A management plan developed by the GSAs to provide a framework in managing the groundwater basin sustainably and to meet the requirements of the SGMA.

Sustainable Groundwater Management Act (SGMA) — SGMA is a package of three bills (AB 1739, SB 1168 and SB 1319) that provide local agencies with a framework for managing groundwater basins in a sustainable manner. Recognizing that groundwater is most effectively managed at the local level, SGMA requires local agencies to achieve sustainability within 20 years. Learn more about SGMA


San Luis Obispo Valley Groundwater Basin (SLO Basin) — A groundwater basin area within the San Luis and Edna Valleys that has been designated as a high priority basin by the State Department of Water Resources (DWR). View interactive map of the SLO Basin

Groundwater Sustainability Agency (GSA) — One or more local agencies may establish a GSA. It is the GSA’s responsibility to develop and implement a GSP that considers all beneficial uses and users of groundwater in the basin. Two GSAs (i.e., the City and County of San Luis Obispo) have been formed for the SLO Basin to cover the whole basin area.

Groundwater Sustainability Commission (GSC) — The GSC is an advisory body that is established by the City and County GSAs to advise the GSAs in connection with preparation of the GSP for the SLO Basin. The GSC is currently comprised of the following individuals and related agencies: Bob Schiebelhut, Chairperson, Edna Valley Growers Mutual Water Company; Mark Zimmer, Vice Chairperson, Golden State Water Company; Dennis Fernandez, Member, Edna Ranch Mutual Water Company/Varian Ranch Mutual Water Company; Andy Pease, Member, City of San Luis Obispo; Adam Hill, Member, County of San Luis Obispo.

GSC Meetings — Quarterly Brown Act public meetings held by the GSC. The general public is encouraged to attend to learn about project progress, ask questions, and provide and share input. Find meeting details on the Calendar

Stakeholder Communication and Engagement Plan (C&E Plan) — Groundwater is best managed at the local level. GSA(s) are required to develop and implement a C&E Plan to ensure the timely, forthright, and consistent communication among all beneficial users of groundwater and stakeholders affected by the GSP.

Groundwater Communication Portal (Portal) — Located at, the Portal is the central online communication hub for public participation and information sharing on the GSP project. Any interested party can subscribe to receive project updates and to review and submit public comment on GSP chapters/sections through the portal. View documents open for public comment

Stakeholder Workshops — Several public workshops are anticipated to be held at specific milestones in the GSP development process to allow for inclusive and meaningful opportunities for affected stakeholders to participate and contribute in the plan design. Find workshop details on the Calendar


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