Notices to Operators – Underground Gas Storage Facilities

​​​​Int​roduction 

The Cal​ifornia Geologic Energy Management Division (CalGEM) issues Notices to Operators (NTOs) to underground gas storage (UGS) operators to communicate important regulatory requirements, safety standards, and operational updates. UGS operators may also be subject to some of the more general NTOs that CalGEM issues to all oil and gas operators, which can be accessed here.


Overview 

CalGEM’s Notices to Underground Gas Storage Operators address matters such as implementation of new or existing regulations, safety directives, testing standards, and compliance deadlines. 
Each NTO may: 

  • Highlight new regulatory requirements or updates. 
  • Clarify expectations for UGS operator compliance with the California Public Resources Code (PRC) and Code of Regulations, title 14 (CCR). 
  • Provide technical specifications for inspection, testing, and reporting. 
  • Reinforce safety, environmental, and public health protection measures. 

UGS operators should review and follow these notices to ensure consistent and full compliance with the PRC and CCR. ​​

​
​Date Issued
​Title / S​​ubject
​Summary
​Link 

​​​December 5, 20​​25 

​Casing Diagram Submission Requirements
​Directs UGS operators to submit updated casing diagrams following well work that does not require an NOI.
​Download PDF​
​
​​​December 5, 20​​25 
​Submitting Well Chemical Inventory Protocols

​Outlines key components of the Well Chemical Inventory Protocol and reminds operators of the January 1, 2026, deadline required by regulation. 
​Download PDF​

​​​​​​​December 5, 20​​25 ​

​WellSTAR Operator User Guide - Upload Well Chemical Inventory Protocol​

​Guidance for UGS operators uploading Well Chemical Inventory Protocols in WellSTAR​

​Down​load PDF​
​
​​​November 5, 20​​25 
​Emergency Response Drills Frequency and CalGEM Participation
​Directs UGS operators to provide copies of Emergency Response Plan updates, including drill schedules, to CalGEM Programs and District Staff, and communicate with the appropriate District and Program seniors on the emergency response drill schedule.
​Download PDF​
​June 26, 20​​25 
​Senate Bill 463: Well Chemical Inventory Deadlines
​Announces final approval of SB 463 Chemical Inventory & Root Cause Analysis regulations effective July 1, 2025. Establishes key compliance deadlines for UGS operators including protocol submission (Jan 1, 2026) and baseline testing (July 1, 2026)
​Download PDF

​​February 6, 20​​25


​​Guidance for Proposed UGS Well Work Operations Feb 2025

​Outlines which underground gas storage well-work activities require an approved Notice of Intention (NOI) before work begins.​
​Download PDF​​
​January 7, 2025
​Updated Protocols for Temperature and Noise Logging
​Outlines updated standards for temperature and noise logging in UGS wells, including run speed limits, anomaly evaluation, and MIT protocol requirements. 
​Download PDF
​October 21, 2024
​Approval to Utilize DarkVision HADES Tool
​Approves the use of DarkVision’s high-resolution acoustic downhole evaluation system (HADES) for casing wall thickness inspections, with data overlap and protocol update conditions.

​​Download PDF

​October 8, 2024
​Annual Well Chemical Inventory Reminder (Superseded) 
​Reiterates PRC § 3181.5 annual reporting requirements for UGS operators to submit chemical inventories by December 31, 2024, and annually thereafter

​​Download PDF

​September 7, 2023
​Well Chemical Inventory Directive (Superseded) 
​Directs UGS operators to submit required well chemical inventories to CalGEM by December 6, 2023, as required under PRC § 3181.5, pending final rulemaking. 
​​Download PDF​
​July 22, 2022
​Unannounced Random Inspection Program (UROW)
​Informs UGS operators of unannounced random well inspection requirements under PRC § 3185 and outlines operator obligations to allow CalGEM access to UGS facilities. ​
​​Download PDF