Frequently Asked Questions

What is groundwater?


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.




What role does groundwater play in California’s water supply?


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 declining groundwater levels in some groundwater basins throughout California. Groundwater use also increases during drought conditions.

  • Californians use more groundwater than any other state in the country, about 14 billion gallons per day. During recent dry years however, groundwater use increased to nearly 18 billion gallons per day.
  • Approximately 31 million Californians get a portion of their drinking water from a public water system that relies on groundwater for at least part of their drinking water supply
  • In addition, up to two million California residents are served either by the estimated 250,000 to 600,000 private domestic wells or by water systems serving fewer than 15 service connections.
  • The availability of clean, fresh groundwater has been credited for making California the largest food and agricultural economy in the country.
The California Department of Water Resources (DWR) estimates that the State’s groundwater reserves equal more than 81 trillion gallons (could fill over 120 million Olympic-sized swimming pools), but not all of it can be used in its current form. That is because some of the groundwater is too salty, too polluted or is too difficult to be extracted from the ground. To learn more, read the California Water Board Groundwater Fact Sheet




What is SGMA?


California depends on groundwater for a major portion of its annual water supply, making sustainable groundwater management essential to a reliable and resilient water system. In recognition of this, in September 2014, Governor Brown signed a three-bill package of legislation into law collectively known as the Sustainable Groundwater Management Act (SGMA). Sustainable groundwater management under SGMA singles out six “undesirable results" to be avoided:

  • Chronic lowering of groundwater levels indicating a significant and unreasonable depletion of supply
  • Significant and unreasonable reduction of groundwater storage
  • Significant and unreasonable seawater intrusion
  • Significant and unreasonable degradation of water quality
  • Significant and unreasonable land subsidence
  • Groundwater-related surface water depletions that have significant and unreasonable adverse impacts on beneficial uses of surface water
What is considered “significant and unreasonable” is left for the local GSAs and stakeholders to decide. At the center of the legislation is the decision that groundwater management is best accomplished at the local level. Under SGMA, Groundwater Sustainability Agencies (GSAs) are tasked with developing and implementing a locally-developed Groundwater Sustainability Plan (GSP) for all groundwater basins designated as medium or high priority by DWR. The legislation allows 20 years to achieve sustainability.




Why are the rules for groundwater management changing?


The SGMA is less a change in the rules governing the use of groundwater and more an introduction of rules where previously there were none. Until SGMA was passed in 2014, the use of groundwater throughout the State was largely unregulated. Anyone could apply for a well drilling permit from their county, and drill and use a well on their property as they saw fit. Among the problems with this approach is that the aquifers are natural formations, not restricted by property lines or political boundaries. We all share the water beneath our feet. What a city or individual does in one area can have a big impact on people living 10, 30 and even 100 miles away. If everyone extracts as much groundwater as they please, without regard for the cumulative impact of all users, we could find ourselves with no access to groundwater, and no way to meet our household, municipal, agricultural and industrial needs. In order to protect this shared resource, it is critical that groundwater users share and coordinate their activities. SGMA was passed to facilitate protection of the resource for all users.




What are the key provisions of SGMA?


  • Protection of water rights: Existing water rights are protected. Nothing in it “determines or alters surface water rights or groundwater rights under common law or any provisions of law that determines or grants surface water rights”.
  • Consideration of multiple stakeholder interests: The legislation requires that a GSA must consider and conduct outreach to a broad range of stakeholders, such as beneficial users of water, environmental interests, disadvantaged communities, tribes, and others.
  • Provides new authorities to the GSAs to manage groundwater: GSAs are granted new tools and authorities which include the authority to conduct investigations, determine the sustainable yield of a basin, measure and limit groundwater extractions, impose fees for groundwater management, and enforce the terms of a GSP.
  • Increases coordination between land use planning agencies and GSAs: Planning and zoning laws are amended to require increased coordination between land use planning agencies and GSAs regarding groundwater plans and updates and modifications of General Plans.
  • Increases availability of information while ensuring privacy protection: The legislation requires aggregated groundwater information for a groundwater basin be provided to the DWR. However, information related to individual groundwater pumpers is limited.
  • State oversight and involvement: The legislation allows for intervention by the State Water Board instances where the GSA does not complete a GSP by the mandated deadline the GSP is deemed inadequate by the DWR and the deficiencies remain inadequately addressed; or the GSP is being implemented and simply does not work. In these cases, the State Water Board is authorized to create an interim plan that will remain in place until the GSA is able to reassume responsibility.




Which groundwater basins are subject to SGMA?


The DWR prioritized 515 groundwater basins in California into one of four categories; high, medium, low or very low priority based on several groundwater related components. All groundwater basins designated as medium or high priority by the DWR are required to form GSAs to develop and implement locally-developed GSPs. A basin’s prioritization is based on several factors such as population and rate of growth, irrigated acreage, and the degree to which the overlying population is dependent on groundwater as their primary source of water. These factors are then totaled and then the basins ranked as high, medium, low or very-low priority. Those basins which are ranked as high or medium priority are subject to SGMA – meaning they must form GSAs and develop GSPs. Three important things to note:

  1. The designation of high or medium priority does not mean the basin is not being managed well. It means that the groundwater basin scored high on factors that indicate that the basin is an important and critical source for the overlying cities and farms. Many high priority groundwater basins are well-managed.
  2. The basin prioritization will change when basin boundaries are modified because changing boundaries changes the factors that go into determining the ranking.
  3. In terms of SGMA, there is no real difference between high and medium priority basins; both are subject to the provisions of SGMA.
Not all groundwater basins are required to establish GSAs and develop GSPs, although other requirements may apply.




What are the roles of the agencies?


SGMA defined new roles for agencies. For local agencies, SGMA requires that local public agency who has water supply, water management or land use responsibilities to form GSAs and to develop GSPs to manage their groundwater basins. In order to effectively implement those plans, SGMA provides new tools and authorities including requiring registration of groundwater wells, measuring and limiting groundwater extractions, imposing fees for groundwater management and enforcing the terms of a GSP. SGMA tasked the DWR with developing regulations to revise groundwater basin boundaries; adopting regulations for evaluating and implementing GSPs and coordination agreements; identifying basins subject to critical conditions of overdraft; identifying water available for groundwater replenishment; and publishing best management practices for the sustainable management of groundwater. DWR is also tasked with evaluating GSPs for adequacy. For enforcement purposes, the legislation allows for intervention by the State Water Board in instances where the groundwater sustainability agency does not complete a plan by the mandated deadline of 2020 or 2022; the plan is deemed inadequate by DWR and remains so after efforts to cure the deficiencies; or the plan is being implemented and simply does not work.




What are the key deadlines for SGMA?


  • January 31, 2020/2022: GSPs must be adopted by 2020 and 2022 for all other remaining groundwater basins designated as high and medium priority that are critically overdrafted and not critically overdrafted, respectively.
  • 2040/2042: All groundwater basins designated as high or medium priority must attain sustainability.




Who is responsible for implementing SGMA?


SGMA requires that all groundwater basins designated as high or medium priority establish GSAs to manage their groundwater basin. Any public agency with water or land use responsibilities can be a GSA; these include cities, counties, municipal water districts, irrigation districts, community services districts, resource conservation districts and water conservation districts. In its simplest form, a groundwater basin can be managed by a single GSA that develops a single GSP. However, some groundwater basins have more than one GSA; those agencies can choose to develop a single GSP or to develop multiple plans that are coordinated by an agreement that covers the entire basin. Sustainable groundwater management is defined as the management and use of groundwater that can be maintained without causing an undesirable result. Undesirable results as defined in SGMA are:

  • Persistent lowering of groundwater levels
  • Significant and unreasonable reductions in groundwater storage
  • Significant and unreasonable saltwater intrusion
  • Significant and unreasonable degradation of water quality
  • Significant and unreasonable land subsidence
  • Surface water depletion having significant and unreasonable effects on beneficial uses
What is considered “significant and unreasonable” is left for the local GSAs and stakeholders to decide.




How will a basin achieve sustainability?


The Act requires that a GSA prepare a GSP that lays out the path that the basin will take to achieve sustainable groundwater management within 20 years. SGMA establishes a broad framework for local agencies to manage groundwater, giving local agencies some flexibility about how to achieve sustainability, as well as how sustainability is defined in the local context. The framework for the GSP has several requirements, including:

  • A description of the physical setting and characteristics of the aquifer system.
  • Current and historical data for groundwater levels, groundwater quality, subsidence and groundwater-surface water interaction, and a discussion of historical and projected water demands and supplies.
  • Maps that include details of the basin and its boundaries and identify existing and potential recharge areas.
  • A succinctly stated sustainability goal for a desired condition that is applicable to the entire basin, how the basin will get to that desired condition, and why the measures planned will lead to success.
  • Measurable objectives, as well as interim milestones in increments of five years, to achieve the sustainability goal in the basin within 20 years.
  • A monitoring plan that will measure progress over time.
  • A description of other applicable local government plans and how the GSP may affect those plans.
  • SGMA also established a process for local agencies to develop an alternative in lieu of a GSP, provided the alternative is functionally equivalent to the elements of a GSP.
After a GSP is adopted, it is then submitted to the DWR who has two years to review the plan for adequacy. If it is found inadequate, GSAs will be given six months to provide remedies. If the DWR determines that the GSP is inadequate and the GSA does not or cannot correct the deficiencies, the State Water Board can designate the basin as “probationary”. If the local agency does not respond within 180 days, the State Water Board is authorized to step in and assume management of the basin until the GSA is able to reassume management with a compliant plan. If the State Water Board intervenes in the management of a groundwater basin, the Board must assess fees to recover cost incurred in administering a probationary basin, such as reporting requirements, investigations, facilitation, monitoring, hearing, enforcement and administrative costs.




What about my domestic well?


Generally, domestic well users meet the SGMA definition of a de minimis extractor, defined as “a person who extracts, for domestic purposes, two acre-feet or less (of groundwater) per year.” Most households with a domestic well that are not watering crops or large areas of landscape are likely de minimis extractors; however, each GSA will determine the management policies that will apply to domestic well users such as whether domestic well users are exempt from management or they may be incorporated into basin management to address the negative impacts they may cause to the basin as a whole. Whether or not SGMA applies to a domestic well owner, the implementation of a GSP will mean changes in the management of groundwater with potential wide-ranging effects. All stakeholders in a groundwater basin subject to SGMA are encouraged to participate in the development of a GSP to ensure a robust and successful outcome. To learn more, read the Domestic Well Users and SGMA Fact Sheet




How can I participate in the management of my groundwater basin?


SGMA sets a new course for groundwater in California that will fundamentally change how groundwater is managed. Ultimately, GSAs will be responsible for deciding who can pump how much and what fees will be charged in order to maintain sustainable groundwater basins through both wet and dry years; these decisions are likely to have far-reaching consequences for local communities and the region. All GSAs are legally required to consider all beneficial uses and users of groundwater, including domestic, agricultural, municipal, environmental, tribes, and disadvantaged communities; it is critical that local water users participate in the process to ensure the management changes address the diverse needs and priorities of the region. A GSP developed through robust involvement with all stakeholders within the basin will ensure the plan’s success. Learn how you can participate





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