Use Attainability Analysis

Designated uses established under the State’s Water Quality Standards (20.6.4 NMAC) may be removed or replaced with a designated use with less stringent criteria only if a Use Attainability Analysis (“UAA”) demonstrates that one of the factors in 40 CFR 131.10(g) is preventing the attainment of the current designated use.

A UAA is a scientific assessment of the factor believed to be preventing the attainment of a designated use. 

Conducting a Use Attainability Analysis

NMED, or other parties, can conduct a UAA in accordance with 20.6.4.15 NMAC.

For parties other than NMED a notice of intent to conduct a UAA along with a work plan must be submitted to the Department and EPA Region 6. At a minimum, the work plan must  include the following:

• The water body of concern and the reasoning for conducting a UAA;
• The source and validity of data to be used to demonstrate whether the current designated use is not attainable;
• The factor under 40 CFR 131.10(g) affecting the attainment of the designated use;
• A description of the data being proposed to be used to demonstrate the highest attainable use;
• The provisions for consultation with appropriate state and federal agencies;
• A description of how stakeholders and potentially affected tribes will be identified and engaged;
• A description of the public notice mechanisms to be employed; and
• The expected timelines outlining the administrative actions to be taken for a rulemaking petition, pending the outcome of the UAA.

Upon approval of the work plan by the Department, the investigation for the UAA may commence, as proposed. Upon completion of the UAA, the proponent shall submit the data, findings and conclusions to the Department and provide public notice of the UAA in accordance with the approved work plan. 

If the findings from the UAA determine that a designated use is not attainable based on one of the factors identified under 40 CFR 131.10(g), the party who conducted the UAA or NMED may petition the Water Quality Control Commission for a public hearing to consider changing the Water Quality Standards. There are several steps in this process and consultation with NMED is strongly encouraged.

What Factors Can Be Used to Change a Designated Use to One with Less Stringent Criteria?

1. Naturally occurring pollutant concentrations prevent the attainment of the use;
2. Natural, ephemeral, intermittent or low flow conditions or water levels prevent the attainment of the use, unless these conditions may be compensated for by the discharge of sufficient volume of effluent discharges without violating State water conservation requirements to enable uses to be met;
3. Human caused conditions or sources of pollution prevent the attainment of the use and cannot be remedied or would cause more environmental damage to correct than to leave in place;
4. Dams, diversions or other types of hydrologic modifications preclude the attainment of the use, and it is not feasible to restore the water body to its original condition or to operate such modification in a way that would result in the attainment of the use;
5. Physical conditions related to the natural features of the water body, such as the lack of a proper substrate, cover, flow, depth, pools, riffles, and the like, unrelated to water quality, preclude attainment of aquatic life protection uses;
6. Controls more stringent than those required by sections 301(b) and 306 of the Act would result in substantial and widespread economic and social impact.

What about Changing a Designated Use to One with More Stringent Criteria?

In accordance with 40 CFR 131.10(i), a Designated Use may not have criteria less stringent than the existing use. For cases in which there is supporting evidence that demonstrates this, the designated use shall be amended accordingly. This type of amendment does not require a UAA, but it does require a demonstration supporting the amendment for the Water Quality Control Commission to consider and base its determination on.