The Underground Injection Control (UIC) Program protects underground sources of drinking water (USDWs) from contamination by the subsurface emplacement of fluids through injection wells. The UIC Program prohibits injection of fluid containing any contaminant if the presence of that contaminant may cause a violation of any primary drinking water regulation or which may adversely affect the health of persons. An USDW is an aquifer, or a portion thereof, which:
- supplies any public water system, or which contains a sufficient quantity of ground water to supply a public water system, and,
- currently supplies drinking water for human consumption, or,
- contains fewer than 10,000 mg/l total dissolved solids (TDS), and,
- is not an exempted aquifer as designated by the procedures in 40 CFR 144.7.
Wells regulated under the UIC Program are defined as bored, drilled, or driven shafts or dug holes whose depths are greater than their largest surface dimension; or, anthropogenically modified sinkholes or other naturally occurring openings into the subsurface; or, subsurface fluid distribution systems.
Class II injection wells are used to inject fluids associated with natural gas storage operations, conventional oil and natural gas production, for enhanced recovery of oil or natural gas, and for storage of hydrocarbons that are liquid at standard temperature and pressure. Class II injection wells are regulated by the Utah Department of Natural Resources, Division of Oil, Gas and Mining. Class I, III, IV, and V injection wells are regulated by the Utah Department of Environmental Quality, Division of Water Quality. Class VI injection wells, for the geologic sequestration of carbon dioxide, are currently regulated by EPA.
All injection wells must be authorized either by rule or by permit. Most injection wells are authorized by rule as long as inventory information is provided according to the rules. The UIC Program sets minimum construction, operating, monitoring, reporting, financial responsibility, closure, and record keeping requirements for all injection operations authorized by permit.