​​​Underground Injection Control

Injection wells have been used in California for nearly 60 years. Some of these wells inject liquids or steam underground to make oil and gas easier to produce. Others return groundwater that is extracted along with oil and gas back underground. The 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.

Under the Safe Drinking Water Act (SDWA), the U.S. Environmental Protection Agency (EPA) has delegated primacy authority over oil and gas injection wells—categorized as Class II injection wells—to the UIC Program. The program must prevent the degradation of underground sources of drinking water (aquifers) where there are injection operations.

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

The UIC Program processes aquifer exemption applications with the EPA to ensure California's compliance with federal law. The EPA may create exemptions under SDWA and allow the injection of fluids associated with oil production into certain aquifers. These aquifers 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.

There are more than 55,000 Class II injection wells in California. UIC staff works with other DOGGR units to collect and manage well data, enforce regulations, and conduct public outreach.



October 29, 2018: DOGGR announced a 15-day public comment period regarding revisions to proposed underground injection control regulations. The proposed rules fortify protection of public health and the environment. The public feedback period concludes November 14, 2018. 

Rulemaking Process

In summer 2018, 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.

Frequently Asked Questions about UIC

Additional Information

Oil and Gas Production: Water Use: Reporting, Senate Bill 1281 (2014)

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

Groundwater Protection Council

For Operators