Basin Boundary Modifications
The Sustainable Groundwater Management Act (SGMA) established a process for to ask DWR to revise the boundaries of existing groundwater basins or subbasins, including establishing new subbasins. We developed the following extensive outreach to SGMA advisory groups, partners, local agencies, and other interested members of the public. The Basin Boundary Emergency Regulations were adopted on October 21, 2015 and the provisions of the emergency regulation went into effect on November 16, 2015.
After the Basin Boundary Emergency Regulations were adopted we provided an online to inform local agencies and the public about the existing Bulletin 118 groundwater basins and other relevant geologic and geographic data. DWR’s enables local agencies to submit their requests for basin boundary modifications online and the public to view those requests and provide comment.
The Draft Basin Boundary Modifications were developed through DWR's technical review of basin boundary modification requests and public comment made during the submission period, January 1, 2018 through September 28, 2018. DWR will hold public meetings to present the Draft Basin Boundary Modifications and technical review process, answer clarifying questions, and receive public comments. After public comment closes, DWR will develop the final Basin Boundary Modifications.
Access the Results
(Updated January 14, 2019)
(Online Web Map)
(Updated January 14, 2019)
|Submission Period and Public Comment Period Opens||January 1, 2018|
|Submission Period Closes||September 28, 2018|
|Draft Basin Boundary Modifications Released and Public Comment Period Opens||November 29, 2018|
|Public Meeting||December 11, 2018|
|Public Comment Period Closes||January 4, 2019|
|California Water Commission Meeting||January 16, 2019|
|Final Basin Boundary Modifications Released||February 2019|
*All dates are subject to change.
Public Meetings and Comments
Public meetings will be held to review the draft recommendations and solicit public comments.
The public comment period opened on November 29, 2018 and closed on January 4, 2019.
Frequently Asked Questions on Basin Boundary Modifications
Answers to frequently asked questions provided below or in the Frequently Asked Questions on Basin Boundary Modifications document.
Bulletin 118 groundwater basin boundaries can be viewed using one of several online mapping applications:
1. Bulletin 118 Website - https://water.ca.gov/Programs/Groundwater-Management/Bulletin-118
2. ArcGIS map and feature services -
3. Mapping Applications:
DWR’s SGMA Data Viewer - https://sgma.water.ca.gov/webgis/?appid=SGMADataViewer
DWR’s Basin Boundary Assessment Tool – https://gis.water.ca.gov/app/bbat/
DWR’s Water Management Planning Tool – https://gis.water.ca.gov/app/boundaries/4. BBMRS - https://sgma.water.ca.gov/basinmod/ (ability to view and download proposed basin boundary modification for each request)
Basin boundaries often do not necessarily coincide with political or legal boundaries. Where a parcel is divided by basin boundaries, each Groundwater Sustainability Agency or other local agency with groundwater management authority will have jurisdiction over that portion of the parcel which is within its boundaries.
SGMA defines a public agency as a local agency that has water supply, water management, or land use responsibilities within a groundwater basin (Wat. Code § 10721(n)).What is considered the definable bottom of a basin or subbasin?
Neither SGMA nor the Department’s regulations include a definition for the definable bottom of a basin, but the phrase is characterized in Bulletin 118-2003 as “rock or sediments of very low permeability if no aquifers occur below those sediments within the basin.What are the key components required to have in a qualified map?
A qualified map is defined in the basin boundary regulations as a geologic map of a scale no smaller than 1:250,000 that is published by the U.S. Geological Survey or the California Geological Survey, or is a map published as part of a geologic investigation conducted by a state or federal agency, or is a geologic map prepared and signed by a professional geologist that is acceptable to the department (23 CCR § 341(u)).
For scientific modifications, a qualified map is required that depicts the lateral boundaries of the aquifers that define the basin or subbasin (23 CCR § 344.14(a)). For scientific modifications involving a hydrogeologic barrier, a qualified map is required that depicts geologic structures or features that could significantly impact or impede groundwater flow (23 CCR § 344.14(b).Who is eligible to submit a basin boundary modification request?
Any local agency may request that the department revise the boundaries of a basin, including the establishment of new subbasins. In addition, any entity may be directed a court in an adjudication action to file a basin modification request.Can DWR make adjustments to basin boundaries without being requested to do so?
The Department makes administrative adjustments to the digital basin boundaries to correct unambiguous errors, such as where a boundary, defined as following a county border, does not, in fact, follow that border (see 23 CCR § 341(b).
The Final 2016 Basin Boundary Modifications were developed through DWR's technical review of basin boundary modification requests and public comment made during the submission period, January 1, 2016 through March 31, 2016. DWR then held a series of public meetings to present the Draft Approved Basin Boundary Modifications, provide an overview of the BBMRS and technical review process, answer clarifying questions and receive further public comments on the Draft Approved Basin Boundary Modification submissions. After a technical review of the requests and public comments, DWR developed the list of 2016 Final Basin Boundary Modifications and adopted them into the 2016 Bulletin 118 Interim Update.
There were many complex issues and challenges associated with the Bulletin 118 – Update 2003 basin boundaries. We met and continue to do so with various organizations, agencies, and individual experts to receive input on these basin boundary issues that create potential difficulties with SGMA implementation. We have and will continue to consider these basin boundary issues and challenges throughout the rule‐making process.
Between April 28th and May 1st of 2015, DWR completed three public listening sessions and one webinar related to the Basin Boundary Regulations. The given during the listening sessions and a recording of the are available for viewing in these internet links.
Based on the feedback collected during the scoping period, which included substantial communication and outreach with numerous local agencies and advisory groups to better understand local perspectives related to boundaries, DWR released a in April 2015.
Local agencies and interested parties had the opportunity to provide input during the preparation of the draft basin boundary regulations and before the regulations were adopted. We held three required public meetings in late August. The draft basin boundary emergency regulations are posted below.
- Draft Basin Boundary Emergency Regulations (July 17 Draft)
- Draft Basin Boundary Emergency Regulations Technical Factsheet (July 17 Draft)
- Public Meetings and Comment Process Factsheet
- California Water Commission (July 15) Basin Boundary Presentation
- Draft Fiscal Cost Analysis for Proposed Modifications to Basin Boundaries Basin Boundary Public Meetings - August 31
- Presentation on Draft Basin Boundary Emergency Regulations
- Recording of Webcast
The proposed emergency regulations have been refined based on public and Commission comments.
- Proposed Basin Boundary Emergency Regulations (October 8 – Clean version)
- Proposed Basin Boundary Emergency Regulations (October 8 – Strikeout version)
- Basin Boundary Emergency Regulations Factsheet (October 8)
Basin Boundary Modification Request System
The Basin Boundary Modification Request System (BBMRS) allows local agencies to request basin boundary modifications and for the public to access basin boundary modification information. Registration and login are required to submit a basin boundary modification request, but are not required to view submitted information.
Basin Boundary Assessment Tool
The Groundwater Basin Boundary Assessment Tool (BBAT) is a web-based application to inform local agencies and the public about the existing Bulletin 118 groundwater basins and other relevant geologic and geographic data.
- Initial Notification Guidance Document
- Modification Request Guidance Document
- Public Input Guidance Document
- Printable Template for Boundary Modification Request Submissions
- Considerations When Submitting Spatial Data
- Groundwater Basin Boundary Webinar Recording 12-17-15
- Presentation from Groundwater Basin Boundary Webinar 12-17-15