Department of Water Resources Determination Regarding the Big Valley Groundwater Sustainability Plan

On October 26, 2023, the Department of Water Resources (DWR) determined that the Big Valley Groundwater Sustainability Plan is "incomplete". A copy of DWR's determination can be viewed here. The Groundwater Sustainability Agencies have 180 days to respond to this determination. 


Big Valley Groundwater Sustainability Plan

On April 9, 2024, the Lassen County Groundwater Sustainability Agency (GSA) approved the revised Big Valley Groundwater Sustainability Plan (GSP), and on April 15, 2024, the Modoc Groundwater Sustainability Agency approved the same GSP. On April 22,2024, said GSP was submitted to the Department of Water Resources. 


Big Valley Groundwater Basin Advisory Committee

The Big Valley Advisory Committee (BVAC) was established to provide local input and direction on the development of a GSP. The BVAC is comprised of one county board member from each county, one alternate board member from each county, and two public members from each county. Moving forward, BVAC will be instrumental in the implementation of the GSP. All BVAC meetings are open to the public.

For current meeting materials see attachments at the bottom of this page.

For past meeting materials see the following page: SGMA Division | Lassen County




In September 2014, California passed the Sustainable Groundwater Management Act (SGMA), requiring that groundwater basins throughout the state be managed by local agencies that are responsible for developing Groundwater Sustainability Plans (GSPs) if a basin has been designated as medium or high priority by the Department of Water Resources (DWR). The Big Valley groundwater basin has been designated as medium priority and therefore a GSP was submitted to DWR on January 27, 2022.

As outlined by SGMA, local agencies with the responsibility of managing a basin are referred to as Groundwater Sustainability Agencies (GSAs), and can only manage portions of a basin within their jurisdiction. Twenty Eight percent of the basin is located within Modoc County and 72% is located within Lassen County. Each county is the GSA for their respective portion of the basin. The Lassen and Modoc GSAs worked together to develop a GSP for the entirety of the basin and will continue to work together to implement that GSP. A Memorandum of Understanding (MOU) between Lassen and Modoc County regarding implementation of the GSP can be found here.

The Modoc and Lassen GSAs were awarded Proposition 1 grant funding to offset the bulk of the cost of developing the GSP. DWR evaluates GSPs within two years of their submittal and will issue a written assessment. If deficiencies are found, the GSAs have 180 days to submit an amended GSP. GSPs have a number of components identified by law and regulation.

The key goal of a GSP is to identify what sustainable conditions are for the Basin. Sustainable conditions will be based on gathering data, performing studies, and implementing projects to determine if the basin has, or will have in the future, any undesirable results for six sustainability indicators, as required in SGMA. The six sustainability indicators are:

  • Chronic lowering of groundwater levels;
  • Reduction of groundwater storage;
  • Seawater intrusion;
  • Water quality degradation;
  • Land subsidence; and
  • Depletion of interconnected streams.

Failure to develop a GSP would have caused the State Water Resources Control Board (SWRCB) to step in and manage the basin, at a substantially higher cost than local management.

Sustainable Groundwater Management Act:

The SGMA is codified as Part 2.74 (Sustainable Groundwater Management Act) of the California Water Code (Section 10720 et seq).  The regulations adopted to enforce the provisions of the Act are found in Section 350 et seq, Division 2, Chapter 1.5, Subchapter 2 of Title 23 of the California Code of Regulations.  The Sustainable Groundwater Management Act (SGMA) became effective January 1, 2015. More information can be found on DWR’s website.

In Lassen County, the Act pertains to the Big Valley Groundwater Basin, which has been designated as a “medium priority” basin by the DWR.  This designation as a medium priority basin requires preparation of a GSP under the Act.  All other groundwater basins in Lassen County, other than Big Valley, are currently designated as “low” or “very low”.  This means that, at least for now, no actions are required pursuant to SGMA for any basin other than Big Valley. More information about DWR’s basin prioritization can be found here.

The SGMA was created to ensure groundwater basins throughout the state are managed to reliably meet the needs of all users, while mitigating changes in the quality and quantity of groundwater. The intent of the Act as described in section 10720.1 of the Water Code is to:

  • Provide for the sustainable management of groundwater basins.
  • Enhance local management of groundwater consistent with rights to use or store groundwater. Establish minimum standards for sustainable groundwater management.
  • Provide local groundwater agencies with the authority and the technical and financial assistance necessary to sustainably manage groundwater.
  • Avoid or minimize subsidence.
  • Improve data collection and understanding about groundwater.
  • Increase groundwater storage and remove impediments to recharge.
  • Manage groundwater basins through the action of local governmental agencies to the greatest extent feasible, while minimizing state intervention to only when necessary to ensure that local agencies manage groundwater in a sustainable manner.

The role of the GSAs was to create a GSP and then to implement and enforce that plan. The plan must include measurable objectives that can be used to demonstrate the basin is sustainably managed within 20 years of implementation.

Role of the Counties:

The Board of Supervisors directed staff to pursue a single plan covering the entire Big Valley Groundwater Basin developed and implemented by both the Lassen and Modoc GSAs.

The role of the two GSAs is to create a GSP and then to implement and enforce said plan. The plan must include measurable objectives (developed by the GSAs) that can be used to demonstrate the basin is sustainably managed within 20 years of implementation. Please see the bottom of the page for the attached Memorandum of Understanding between the Lassen and Modoc County GSAs.

The Act gives the GSA many authorities including the ability to adopt rules, regulations, ordinances and resolutions; conduct investigations; impose fees; require well registration, wellhead metering, monitoring, and reporting; allocating groundwater production; taking enforcement actions; and control groundwater extraction by regulating, limiting or suspending extractions from wells. It is up to the GSA which (if any) authorities will be exercised.

The cost to prepare the GSP was significant, but largely offset by Proposition 1 grant funding. The cost to enact and implement the Plan will be significant as well in part due to the technical requirements to understand the resource at the level of detail needed. Additionally, actions taken with the implementation of the GSP may or may not be exempt from the California Environmental Quality Act (CEQA) which requires public agencies to consider the environmental consequences of their discretionary actions. This process can be quite time-consuming and expensive.

That said, it is anticipated that State Water Board intervention would result in a much greater cost than the Counties assume responsibility for as GSAs, especially considering that preparation of a GSP by a local agency is exempt (see Water Code Section 10728.6) from the California Environmental Quality Act (CEQA) but preparation of plans by a State agency is not exempt. Costs for the Water Board to prepare and implement a plan would be passed onto property owners.

How to Participate

Those who wish to be informed and/or involved in activities related to SGMA and groundwater management in Big Valley should join the interested parties list for one or both of the GSAs. People on the interested parties lists are under no obligations, and will receive information about GSP development periodically, including meeting announcements and opportunities to provide input and become more involved. If you would like to be included on the interested parties list for the Big Valley Basin, please visit the GSA websites or contact the counties directly at the phone numbers and email addresses listed below.

Lassen County at (530) 251-8269 and

Modoc County at (530) 233-6201 and



Contact Information: 

Contact Information

707 Nevada Street Ste 5
96130 Susanville , CA
Mon - Fri:
7:00 am-12:00 pm , 1:00 pm-4:00 pm
Sat - Sun:
Inspection Line
Fax Line
(530) 251-8373