Groundwater Sustainability Plan
A Groundwater Sustainability Plan (GSP) is a 20-year plan to ensure the sustainable use of groundwater within a groundwater basin. The Petaluma Valley Groundwater Sustainability Agency (GSA) is required by state law, the Sustainable Groundwater Management Act (SGMA), to develop a GSP by 2022. The goal of the GSP is to establish a standard for “sustainability” of groundwater management and use, and to determine how the basin will achieve this standard. For a thorough description of the GSP process and requirements, read this document from the Department of Water Resources (DWR). DWR will also provide ongoing support through Best Management Practices and Guidance Documents.
Below is the Table of Contents for the Petaluma Valley GSP, which includes links to draft sections that have been reviewed by the the Advisory Committee. For the Sustainable Management Criteria (Section 4), there are links to presentations and draft proposals that the Advisory Committee considered.
The public will have an opportunity to comment on updated draft sections and figures in Fall 2020. For questions about the sections and figures, contact the GSA.
Table of Contents
Section 4 of the GSP focuses on Sustainable Management Criteria (SMCs) for preventing the following six undesirable results: chronic lowering of groundwater levels, land subsidence, seawater intrusion, degradation of water quality, reduction of groundwater storage, and depletion of interconnected surface water.
A primer on SMC terminology can be found here.
Materials for Section 4
The actual text for Section 4 will be written as the draft SMCs are being developed (see process description below). The following materials were provided to the Advisory Committee and Board as they consider specific SMCs. These materials are provided for explanatory purposes but should not be considered draft GSP text.
Sustainable Management Criteria: Chronic lowering of groundwater levels
Sustainable Management Criteria: Land subsidence caused by groundwater pumping
- Background & Strawman
Sustainable Management Criteria: Seawater intrusion caused by groundwater pumping
- Background & Strawman
Sustainable Management Criteria: Degradation of Water Quality (in development)
Sustainable Management Criteria: Depletion of Groundwater Storage (in development)
Sustainable Management Criteria: Depletion of Interconnected Surface Water (in development)
Description of Section 4 Process
The GSA will spend 2020 developing draft SMCs. In general, the process for development of SMCs consists of the following steps:
• Development of the technical methodology used to evaluate the SMCs. The methodology describes the procedures, methods and data to be used for the evaluation of Minimum Thresholds (MT) and Measurable Objectives (MO)
• Determination of MTs and MOs for each SMC.
• Description of significant and unreasonable conditions.
• Definition of undesirable results: The initial step for developing the technical methodology involves staff working closely with the Advisory Committee and ultimately vetting the recommended approach with the Board and the public. Developing SMCs is an iterative process, and will be revisited when all draft SMCs are developed and after an assessment of what projects or management actions are needed to meet the draft SMC requirements.
Much of this assessment will rely on using the groundwater model to simulate future conditions relative to the requirements of the draft SMCs. If based on this analysis and public feedback, the Board determines that the draft SMC(s) would require projects or management actions that are not feasible (e.g., technical, economic), the SMCs will be revised to ensure that their implementation is feasible.
Share Your Thoughts and Concerns about the GSP
The Petaluma Valley GSA deeply values the voice of community partners throughout the process of creating the GSP. The GSA wants input from people who live or work in the basin, who own wells in the basin, who rely on groundwater for their livelihood, and who care about the basin’s plants and animals. In other words, if you care about groundwater, the Petaluma Valley GSA wants to hear from you.
The California Department of Water Resources has prepared several useful guidance documents on preparation of GSPs, including the following:
Additional materials and guidance can be found on DWR’s website.
Groundwater Sustainability Plan Development Timeline
DWR developed detailed requirements and regulations for successful GSPs. The GSP must describe and identify:
- Who is involved in the GSA
- The basin’s geology and hydrogeology
- How the GSA will define and measure sustainability
- Programs and projects that get the basin to sustainability
- How the GSP will be implemented.
Describe the Groundwater Basin
The GSP will include background organizational information about the basin, including maps of town and cities, land use data, well density information and descriptions of existing groundwater management activities and general plans. Here are some examples of information to be included:
- Geologic data
- Historical and current groundwater conditions and budgets
- Future groundwater budget
- Information about existing monitoring programs
Define and Measure Sustainability
One of the primary tasks of the GSP is to define sustainable groundwater management for the Petaluma Valley basin. This definition will be based on six sustainability indicators described by SGMA. Each sustainability indicator is based on avoiding one of the major outcomes of unsustainable groundwater use.
The GSP will set measurable thresholds and measurable objectives for each sustainability indicator. The GSA will consider scientific data and input from stakeholders and the community to create a GSP that demonstrably avoids these undesirable results.
Fundamental to developing Sustainable Management Criteria (SMC) is understanding the language, and understanding how the concepts relate to each other. This cheat sheet provides a plain language discussion of key terms, and illustrates how the concepts are interrelated.
Lowering Groundwater Levels
Reduction of Storage
Degraded Groundwater Quality
Surface Water Depletion
Projects and Management Actions
- Increased use of recycled water to decrease reliance on groundwater and slow pumping.
- Stormwater recharge projects to increase groundwater levels.
- Groundwater banking projects to store excess water in depleted aquifers.
- Managing water demand through conservation or other methods.
- Other innovative strategies to avoid the undesirable results listed above.
The GSP must demonstrate that these projects and actions will ensure sustainability in the basin for 30 more years (until 2072). The GSP also must include plans to fund these projects, and include backup or supplemental plans in case it is determined that the preferred projects and programs are not adequate.
Submission and Evaluation
Once completed, the GSPs will be submitted to the California Department of Water Resources (DWR) for review and evaluation. There will be a 60-day public comment period during this time. DWR will determine whether the GSP meets the requirements of SGMA and whether it will achieve the basin’s sustainability goal. DWR will respond with one of three outcomes:
- Determined incomplete. If the GSP passes basic initial criteria, but is determined by DWR to be incomplete, the GSA may be able to correct and resubmit the GSP.
- If DWR determines that a GSP is inadequate, the State Water Resources Control Board (SWRCB) may intervene in that basin’s groundwater management.