UIC PROGRAM Ongoing Confirmation of Aquifer Exemptions

The Underground Injection Control program (UIC) in California has been administered by the Division of Oil, Gas and Geothermal Resources (DOGGR) for decades under authority granted by the United States Environmental Protection Agency (US EPA). The program is designed to protect aquifers that qualify as underground sources of drinking water (USDW) in compliance with the federal Safe Drinking Water Act (SDWA). Under the law, DOGGR is authorized to permit underground injection for Class II wells into formations that do not contain USDWs or that contain only exempted aquifers.

Class II wells are those used in connection with oil and natural gas production. Although DOGGR has primacy over the Class II UIC program, all aquifer exemptions must be approved by US EPA.

Oil production in California relies on the use of permitted Class II injection wells for enhanced oil recovery operations and for disposal of produced water.

“Oil production in California relies on the permitted use of Class II injection wells for enhanced oil recovery operations and for disposal of produced water.”

By the numbers:

  • There are 50,000 Class II injection wells
  • 80-85% of oil produced in California relies on injection wells
  • The industry produced about 130 billion gallons of water (70%+ is treated and used in enhanced oil recovery operations and <30% disposed in Class II injection wells)
  • Kern County oil companies also provide over 10 billion gallons of treated, reclaimed water per year to farmers who desperately need it.

California’s Class II injection wells operate under specific state permits issued by DOGGR. Most injection for enhanced oil recovery occurs into oil-bearing zones that do not qualify as USDWs.

DOGGR’s robust workplan has demonstrated compliance & tightened governance

Aquifer Exemption Reviews: The focus is on the quality of the aquifer being exempted, and hydrogeological containment of injected fluids.

  • Under the SDWA, aquifers that meet the definition of a USDW may be determined to be exempt if the aquifer: (1) does not currently serve as a source of drinking water; and (2) it cannot now and will not in the future serve as a source of drinking water because, among other things, (a) it is in a hydrocarbon bearing zone; (b) it is at a depth or location which makes recovery of water for drinking water purposes economically or technologically impractical; (c) it is so contaminated that it would be economically or technologically impractical to make it fit for human consumption; or (d) the total dissolved solids (TDS) content of the groundwater is more than 3,000 and less than 10,000 mg/l and it is not reasonably expected to supply a public water system.
  • Aquifers that contain 10,000 mg/l or more TDS do not qualify as USDWs and do not require exemption.
  • The State requires aquifer exemption application packages to be supported by strong technical data and robust evaluations.
  • All aquifer exemption packages prepared by DOGGR are thoroughly reviewed and subject to concurrence by the State Water Resources Control Board (SWRCB) prior to submittal to the US EPA for approval.
  • The US EPA is responsible for approving all aquifer exemption applications, ensuring all regulatory criteria are met. Once EPA has approved an aquifer exemption, Class II wells may be permitted to inject into the exempted aquifer.

“State regulators are working transparently and proactively with the public during this review process to share information and encourage public participation.”

Transparent Process:

State regulators are working transparently and proactively with the public during this review process to share information and encourage public participation:

  • DOGGR submits regular progress reports to the US EPA.
  • DOGGR has conducted regional workshops.
  • All aquifer exemption packages are subject to public notice and comment.
  • All documents are available online for review.

UIC Regulatory Update:

  • DOGGR adopted emergency and final regulations with a schedule to process and obtain US EPA approval of aquifer exemptions.
  • Over the next year, DOGGR is also updating regulations that govern the UIC program.
  • DOGGR is compiling a searchable database of all injection wells for improved management of permitting and enforcement.
  • DOGGR is adding staffing to review and process aquifer exemption applications and UIC permits.

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