New Mexico
Environment Department

Contact Information:
(505) 827-2855 MAIN // 1-800-219-6157 (toll free)
Environmental Emergencies:
505-827-9329 (24 hrs)

Surface Water Quality

Use Attainability Analysis


Designated uses established under the State’s Water Quality Standards may be removed or made less stringent only if a Use Attainability Analysis (UAA) demonstrates that attaining the current designated use is not feasible due to one of the factors listed in 40 CFR 131.10(g). 

A UAA is the scientific assessment of the factors believed to be affecting the attainment of a designated use. 

A UAA is not applicable for a site-specific criterion investigations to which the established designated use is appropriate but a particular criterion for that use is being evaluated based on unique characteristics of a particular waterbody or location.  

For further information, contact  Jennifer Fullam, Water Quality Standards Coordinator.

Who Can Conduct a Use Attainability Analysis

NMED can conduct a UAA in accordance with NMAC.

Parties other than NMED may also conduct a UAA by submitting notice and a work plan to the Department and EPA Region 6 stating the intent to conduct a UAA.  The work plan must  include the following:

  • The water body being consider under the analysis
  • The evidence suggesting it is not able to attain the current designated use(s)
  • The primary factor under 40 CFR 131.10(g) affecting the attainment of the designated use
  • The scope of data currently available and how it will be used to demonstrate the factor
  • The scope of data proposed to be gathered under the analysis and how it will be used to demonstrate the factor
  • The provisions for public notice (refer to requirements associated with development of Water Quality Standards and rulemaking)
  • The proposed means of consultation with appropriate Federal, State and Tribal agencies.  

Upon approval of the work plan by the Department, the investigation for the UAA may commence, as proposed.  Upon completion of the UAA, all data, findings and conclusions must be submitted to the Department and EPA Region 6. 

What is the Process Once a Use Attainability Analysis is Completed?
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?
  1. Naturally occurring pollutant concentrations prevent the attainment of the use; or
  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; or
  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; or
  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; or
  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; or
  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.
Are There Different Types of Use Attainability Analysis?

All UAAs involve analysis of attainment of a designated use.  Most focus on either those uses associated with protection of Aquatic Life or those protecting human health through either primary or secondary contact.  

The Hydrology Protocol is a  standardized survey method that was developed by the Department to determine the appropriate aquatic life and recreational uses supported by the hydrology of a given stream or river, as seen when default intermittent aquatic life uses are applied to ephemeral waterbodies.

The information gathered from a Hydrology Protocol survey may not be used in place of a UAA, but rather to support the findings of a UAA.  For more information regarding the Hydrology Protocol and it’s specific applications, please refer to New Mexico’s Water Quality Management Plan and Continuing Planning Process (WQMP/CPP)

What UAAs Have Been Conducted So Far?

Some UAAs are taken to the WQCC during a Triennial Review of the State’s Water Quality Standards (WQS) while some have been taken independently outside of the Triennial Review.  

The Department maintains a list of all WQS amendments which should be referenced prior to beginning any new study.   

Other Resources


New Mexico Water Quality Act NMSA §74-6-1

Federal Clean Water Act

40 CFR Subchapter D Water Programs §130 and§131 


New Mexico’s Water Quality Standards 

List of WQS Amendments 

Hydrology Protocol


Air-water correlation and summary white paper