​​​Underground Injection Control

The oil and gas industry drills injection wells for several purposes. Some of these wells inject liquids or steam into underground oil and gas reservoirs to push the resources toward production wells. Others return groundwater that is extracted along with oil and gas to the reservoir. The aptly named Underground Injection Control (UIC) Program in the Division of Oil, Gas, and Geothermal Resources (DOGGR) administers state regulations for the permitting, drilling, inspecting, testing, and sealing of these wells. Additionally, DOGGR has proposed new regulations that fortify protection of public health and safety, and the environment under review after taking public comment.

The UIC Program has a similar obligation per federal law. Under the Safe Drinking Water Act, the U.S. Environmental Protection Agency (EPA) has delegated primacy authority over oil and gas injection wells, termed Class II injection wells to the UIC Program. The program must prevent the degradation of underground sources of drinking water where there are injection operations.

How Water is pumped up with oil and injected back into the ground

Also within the purview of the UIC Program is the processing of aquifer exemption applications with the EPA. The EPA may create exemptions under the Safe Drinking Water Act and allow the injection of fluids associated with oil production into certain aquifers. These underground geologic formations are not sources of drinking water, nor are they likely to be in the future because they naturally contain petroleum or high levels of elements such as arsenic or boron.

DOGGR collaborates with the State Water Resources Control Board to ensure that any useful water is protected.

Injection wells have been used in California for nearly 60 years; there are more than 55,000 such Class II wells. UIC staff works with other DOGGR units to collect and manage well data, enforce regulations, and conduct public outreach.



DOGGR is currently reviewing public comments received on the new (2018) UIC draft regulations.

Rulemaking Process

DOGGR and the State Water Resources Control Board (SWRCB) adopted revisions to the 1988 Memorandum of Agreement (MOA) regarding administration of the UIC program for Class II wells, discharges to land, and other related issues.

Revised MOA between DOGGR and SWCB, July 31, 2018 (PDF)

Frequently Asked Questions (FAQs)

Additional Information

U.S. Environmental Protection Agency: UIC and Drinking Water

Groundwater Protection Council

For Operators