1. (1) The division may identify, by narrative description, illustrations, maps, or other means, and shall protect as a USDW, each aquifer or parts of an aquifer that meet the definition of an USDW, except where there is an applicable aquifer exemption under Subsections (2) and (4), or an expansion to the areal extent of an existing Class II enhanced oil recovery or enhanced gas recovery aquifer exemption for the exclusive purpose of Class VI injection for geologic sequestration under Subsection (4). Other than approved aquifer exemption expansions that meet the criteria set forth in Subsection (3), new aquifer exemptions may not be issued for Class VI wells. Even if an aquifer has not been specifically identified by the division, it is a USDW if it meets the definition.

2. (2) After notice and opportunity for a public hearing the division may identify, by narrative description, illustrations, maps, or other means, and describe in geographic or geometric terms, such as vertical and lateral limits and gradient, which are clear and definite, any aquifer or parts of an aquifer that the division proposes to designate as exempted aquifers if they meet the following criteria:

   1. (a) The aquifer does not currently serve as an USDW; and

   2. (b) The aquifer cannot now and will not in the future serve as an USDW because:

      1. (i) It is mineral, hydrocarbon or geothermal energy producing or can be demonstrated by an operator as part of a permit application for a Class II or Class III operation to contain minerals or hydrocarbons that, considering their quantity and location, are expected to be commercially producible;
      2. (ii) It is situated at a depth or location that makes recovery of water for drinking water purposes economically or technologically impractical;
      3. (iii) It is so contaminated that it would be economically or technologically impractical to render ground water fit for human consumption; or
      4. (iv) It is located over a Class III well mining area subject to subsidence or catastrophic collapse; or
   3. (c) The total dissolved solids 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.
   4. (d) Interested parties desiring to have an aquifer exempted from classification as a USDW, shall submit to the division an application that includes sufficient data to justify the proposal. The division shall consider the application and if appropriate, will advise the applicant to submit a request to the board for an aquifer exemption.

   5. (e) The areal extent of an aquifer exemption for a Class II enhanced oil recovery or enhanced gas recovery well may be expanded for the exclusive purpose of Class VI injection for geologic sequestration under Subsection (4) if it meets the following criteria:

      1. (i) It does not currently serve as a USDW; and
      2. (ii) The total dissolved solids content of the groundwater is more than 3,000 mg/L and less than 10,000 mg/L; and
      3. (iii) It is not reasonably expected to supply a public water system.
3. (3) No designation of an exempted aquifer submitted as part of the UIC program shall be final until approved by the USEPA. No designation of an expansion to the areal extent of a Class II enhanced oil recovery or enhanced gas recovery aquifer exemption for the exclusive purpose of Class VI injection for geologic sequestration of carbon shall be final until approved by the USEPA as a substantial revision of the state's UIC program in accordance with 40 CFR 145.32.

4. (4) Expansion to the Areal Extent of Existing Class II Aquifer Exemptions for a Class VI Well. The operator of a Class II enhanced oil recovery or enhanced gas recovery well may request that the division approve an expansion to the areal extent of an aquifer exemption already in place for a Class II enhanced oil recovery or enhanced gas recovery well for the exclusive purpose of Class VI injection for geologic sequestration. Such requests are treated as a substantial program revision to the division's UIC program and will not be final until approved by USEPA.

   1. (a) The operator of a Class II enhanced oil recovery or enhanced gas recovery well that requests an expansion of the areal extent of an existing aquifer exemption for the exclusive purpose of Class VI injection for geologic sequestration must define, by narrative description, illustrations, maps, or other means and describe in geographic or geometric terms, or both, such as vertical and lateral limits and gradient, that are clear and definite, any aquifer or parts of an aquifer that are requested to be designated as exempted under Subsection (3).

   2. (b) In evaluating a request to expand the areal extent of an aquifer exemption of a Class II enhanced oil recovery or enhanced gas recovery well for Class VI injection, the division must determine that the request meets the criteria for exemptions. In making the determination, the division shall consider:

      1. (i) Current and potential future use of the USDWs to be exempted as drinking water resources;
      2. (ii) The predicted extent of the injected carbon dioxide plume, and any mobilized fluids that may result in degradation of water quality, over the lifetime of the project, as informed by computational modeling performed pursuant to Section R644-8-2, to ensure that the proposed injection operation will not at any time endanger USDWs, including non-exempted portions of the injection formation; and
      3. (iii) Whether the areal extent of the expanded aquifer exemption is of sufficient size to account for any possible revisions to the computational model during reevaluation of the area of review pursuant to Subsection R644-8-3(2).

KEY: oil and gas law

Date of Last Change: July 31, 2025

Authorizing, and Implemented or Interpreted Law: 40-11-3