​​​Underground Injection Control (UIC) News and Information

UIC Project Applications Under Review


Aquifer Exemption Compliance Schedule Regulations

EPA Correspondence and Guidance Documents

On Thursday, August 16, 2018 the Division of Oil, Gas, and Geothermal Resources of the Department of Conservation and the State Water Resources Control Board sent an update to the U.S. Environmental Protection Agency on the State agencies’ ongoing corrective review of underground injection well information. The objective of the review has been to identify wells that may have been improperly permitted to inject produced fluids into non-hydrocarbon producing, non-exempt aquifers. This update focuses particular attention on those wells that may have the highest risk to California aquifers from contamination due to oil and gas production.


Division, State Water Board, and US EPA Aquifer Exemption Workshops

Joint workshops conducted by the Division, the State Water Board, and the US EPA were held in Bakersfield and the L.A. Basin. These workshops were intended to provide a brief history of the State’s primacy delegation from US EPA, as well as an outline of the data requirements and process for requesting an aquifer exemption under the Safe Drinking Water Act. All three agencies provided short presentations regarding their specific role, and were available to answer general questions about the aquifer exemption application process.

Copies of the presentations by the three agencies are found below:

The link below is to a list of issued well permits that may currently have a corresponding well injecting into an aquifer potentially needing an aquifer exemption, pursuant to the US EPA’s request.

This list is best understood as a list of well permits, rather than wells. Wells can be proposed and permitted without ever being drilled or converted to an injection well. Even where a well has been drilled, it may already have been plugged and abandoned or issued other orders preventing injection. Determining the current status of the wells listed here is part of the Division’s February 6, 2015, response to the US EPA. This list was generated by identifying one or both of the following characteristics:

  • The permit is for a well located outside the productive limits of a field as those limits were identified in the State’s Primacy application to the US EPA;
  • The permit is for a well injecting within the productive limits but into multiple zones, one of which may not be exempted by the Memorandum of Agreement (MOA) with the US EPA. The Division acknowledges that many of these wells may not need an aquifer exemption, but a formal determination cannot be made until an evaluation, of the specific well(s) and injection zone(s), is completed.

Please note that the evaluation of these well permits has begun and the list continues to change. However, to be consistent with the US EPA’s letter to the Division dated December 22, 2014, and the Division’s response on February 6, 2015, the list contains the permitted wells into non-hydrocarbon producing zones as of August 2014, and a list of the enhanced oil recovery permitted wells as of October 2014. The Division will update the list periodically.


Update on the Memorandum of Agreement (MOA) with the United States Environmental Protection Agreement (EPA)

There are two competing versions of the September 29, 1982 Memorandum of Agreement between the Division of Oil, Gas and Geothermal Resources and the United States Environmental Protection Agency. California’s primacy delegation was made based on one or both of versions of this document. Some related documentation is also included.


Aquifer Exemption Guidance