Inter-Basin Coordination

Inter-Basin Coordination in the Northern Sacramento Valley

In the Sacramento Valley, inter-basin coordination is critical as Groundwater Sustainability Agencies develop their Groundwater Sustainability Plans. We all recognize the interconnectedness of groundwater in the subbasins that together make up the larger Sacramento Valley groundwater basin.

Coordination among Groundwater Sustainability Agencies (GSA) can be formalized through Coordination Agreements. These are voluntary, and the components of such agreements are described in the Groundwater Sustainability Regulations in Article 8 (PDF).

Informal exchange of information and collaboration occurs between staff and consultants working on GSPs in subbasins throughout the region. In addition, Tania Carlone and Mariana Rivera-Torres of the Consensus Building Institute (CBI) are facilitating inter-basin coordination. The effort began with conversations between County staff from Tehama, Glenn, Colusa, and Butte to identify priorities and resources available for inter-basin coordination.

The following provide an overview of the scope and timeline of the efforts:

• Inter-Basin Coordination Efforts (Flyer) (PDF)
• Inter-Basin Coordination Efforts (Slides) (PDF)

Framework for Inter-Basin Coordination

View the Final Northern Sacramento Valley Inter-basin Coordination Report (PDF).

This report outlines a framework for inter-basin coordination for sustainable groundwater management in the Northern Sacramento Valley. It describes a menu of options for ongoing communication and collaboration between and among groundwater subbasins over the twenty-year implementation of the Sustainable Groundwater Management Act (SGMA). This framework can be used by GSA to support Groundwater Sustainability Plan (GSP) development and implementation in several ways.

1. This inter-basin coordination report could be included as an appendix to the GSP and could be updated at regular intervals.
2. Individual subbasins could incorporate sections of the report into the body of the GSP, depending upon specific boundary conditions at adjoining subbasins.
3. Subbasins could draw on the inter-basin coordination framework if they would like to consider entering into one or more voluntary inter-basin agreements during GSP implementation (GSP Regulations in Article 8, Sec 357.2.

Staff throughout the region will present the framework as a supporting document to guide and inform discussions with GSA Boards and at other subbasin-specific public venues, such as advisory committees, groundwater commissions, or other relevant venues. These discussions could help determine GSA priorities and the desired approach each GSA would like to take to draw upon the inter-basin coordination framework within their individual GSPs.

Subbasin staff acknowledge that while this report builds upon a long-standing history of regional collaboration, this is just the beginning of inter-basin coordination efforts under SGMA. Therefore, this framework will be continually refined throughout GSP implementation and inter-basin coordination activities will occur on an ongoing basis.

Implementing SGMA in the Northern Sacramento Valley

For more information about activities and GSP development in individual subbasins, visit their websites:

While efforts have mainly focused on the subbasins identified, coordination will occur, as warranted, with other subbasins to the north and south (Anderson and North Yuba).

Technical Coordination

Integrated hydrologic models (surface water-groundwater models) are a useful data analysis tool to enhance our understanding of groundwater dynamics, estimate water budgets, and support development of portions of Groundwater Sustainability Plans. The following outlines which model is being used in various subbasins in the region:

• Butte: Butte Basin Groundwater Model 2020
• Wyandotte Creek: Butte Basin Groundwater Model 2020
• Corning: Refined version of C2VSim-FG v.1.0 (pending DWR release of v.1.0)
• Colusa: Refined version of C2VSimFG Beta 2
• Antelope: Tehama County Integrated Hydrologic Model (revised SVSim model)
• Bend: Tehama County Integrated Hydrologic Model (revised SVSim model)
• Bowman: Tehama County Integrated Hydrologic Model (revised SVSim model)
• Red Bluff: Tehama County Integrated Hydrologic Model (revised SVSim model)
• South Battle Creek: Tehama County Integrated Hydrologic Model (revised SVSim model)

The following information about the modeling tools and their development has been compiled by the technical teams working in these subbasins.

• Highlights of Compiled Model Information (PDF)
• Compiled Modeling Tools Spreadsheet (XLSX) - this table contains descriptions for the main characteristics of the models being used to support SGMA implementation throughout the region
• To compare water budget results from the different subbasins, the Draft Spreadsheet Template (XLSX) has been developed. Each consultant team will fill it out for their respective subbasin(s) and then the information can be compared and will be made available to the public.

Sustainable Management Criteria

Staff from the subbasins in the region worked together to compile information about how the Sustainable Management Criteria were set for each of the six Sustainability Indicators in each subbasin’s GSP.  Compilation of the SMC summary table (completed in January 2022) concludes the coordination efforts of the GSAs during GSP development as facilitated by CBI.