Surface Water Quality Bureau
Water Quality Standards
Use Attainability Analyses

A use attainability analysis (UAA) is a scientific assessment of the factors affecting the attainment of a designated use. Designated aquatic life or contact uses in the Standards may not be removed or “downgraded” – made less stringent – unless a UAA demonstrates that attaining the assigned designated use is not feasible due to one of the factors listed in 40 CFR 131.10(g). An “existing use” may not be removed at all unless a use requiring more stringent criteria is added. An existing use is defined as, “a use actually attained in a surface water of the state on or after November 28, 1975, whether or not it is a designated use.” (20.6.4.7 NMAC)

NMED or any other party may conduct a UAA; the Standards explain the requirements at 20.6.4.15 NMAC. Changes to water quality standards based on a UAA must be adopted by the Water Quality Control Commission (WQCC) after a public hearing and then must be approved by the US Environmental Protection Agency (EPA).

 NMED has prepared a UAA for the lower Dry Cimarron River and is currently working on one for Galisteo Creek. Information about these investigations and how to be involved is provided below. Both UAAs are reviewing the designated aquatic life uses. Part of the analysis rests on a Water-Air Temperature Correlation that NMED has developed based on average air temperatures and on long-term water temperature data collected by the SWQB from streams across the state.