A Guide to California’s Groundwater Sustainability Plans

The document explains the requirements of California's Sustainable Groundwater Management Act (SGMA), detailing the components of Groundwater Sustainability Plans (GSPs) and the role of Groundwater Sustainability Agencies (GSAs). It identifies six 'undesirable results' that plans must avoid, such as land subsidence and seawater intrusion, and explains the technical tools used to manage these, including water budgets and hydrologic models. The guide emphasizes the subjective nature of 'sustainability' and provides a framework for stakeholders to engage in the planning process, set minimum thresholds, and collaborate with technical experts to ensure plans reflect community values.

• The Sustainable Groundwater Management Act (SGMA) requires each groundwater basin in California to develop a groundwater sustainability plan (GSP) to be approved by the California Department of Water Resources. These plans must be achieved by 2040, or 2042 for lower-priority basins.
• A GSP must contain four primary components: a description of the plan area and basin setting (including a water budget), a sustainability goal that avoids six specific 'undesirable results', projects and management actions to reach that goal, and a monitoring plan.
• There are six types of 'undesirable results' that sustainability plans aim to avoid: significant and unreasonable reduction of groundwater storage, lowering of groundwater levels, seawater intrusion, degraded water quality, land subsidence, and depletions of interconnected surface water.
• Sustainability is defined locally and is largely subjective, as there is no single technical definition. Communities must decide the acceptable level of damage or the desired amount of repair for each undesirable result, though they cannot threaten the sustainability goals of neighboring basins.
• GSAs use 'minimum thresholds' (numeric failure points) and 'measurable objectives' (forward-looking goals) to manage basins. Minimum thresholds may vary by time (e.g., summer vs. winter) or space (e.g., populated vs. unpopulated areas).
• Water budgets and hydrologic models are essential technical tools. While water budgets track total inflows and outflows to determine safe yield, hydrologic models provide three-dimensional, geographically specific data to test 'if...then' scenarios and project future conditions including climate change.
• SGMA mandates the active involvement of diverse stakeholders, including the general public, agricultural users, domestic well owners, municipal well operators, public water systems, local land-use planning agencies, environmental interests, surface water users, the federal government, California Native American tribes, and disadvantaged communities.

APA

Union of Concerned Scientists (2017). A Guide to California’s Groundwater Sustainability Plans. https://www.ucs.org/sites/default/files/attach/2017/10/ws-report-CAtoolkit-en.pdf

Chicago

Union of Concerned Scientists. A Guide to California’s Groundwater Sustainability Plans. 2017. https://www.ucs.org/sites/default/files/attach/2017/10/ws-report-CAtoolkit-en.pdf.

Wikipedia

{{cite report |author=Union of Concerned Scientists |title=A Guide to California’s Groundwater Sustainability Plans |date=September 2017 |url=https://www.ucs.org/sites/default/files/attach/2017/10/ws-report-CAtoolkit-en.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{unionofconcernedscientists2017guide, author = {{Union of Concerned Scientists}}, title = {{A Guide to California’s Groundwater Sustainability Plans}}, institution = {Union of Concerned Scientists}, year = {2017}, month = sep, url = {https://www.ucs.org/sites/default/files/attach/2017/10/ws-report-CAtoolkit-en.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }