Use-Attainability Analysis (UAA)

In many cases, there are conditions at a site that limit the potential for aquatic life to “attain” a use classification. For example, a cold water (trout) use is not attained in a low-elevation warm water stream. And, sometimes, fish are not supported (attained) at all in low flow or ephemeral streams. The study approach to determine what factors can limit an aquatic life classification is a use-attainability analysis, or UAA. This is the formal EPA method needed to subclassify or downgrade an aquatic life use and is the first step in the development of site-specific standards.