Why Develop a Hydrology Protocol?
Perennial, intermittent, and ephemeral, as they pertain to all types of waterbodies, are defined in section 20.6.4.7 NMAC of New Mexico’s water quality standards (WQS). Amendments adopted by the Water Quality Control Commission in 2005 created new sections in the WQS that established designated uses and criteria for unclassified waters. Three separate provisions addressed ephemeral waters, intermittent waters, and perennial waters. The new provisions responded to a long-standing EPA concern that all waters, not only specifically identified classified waters, must be protected by WQS in compliance with the Clean Water Act (CWA). EPA supported the concept of these provisions, but disagreed that the designated aquatic life and recreation uses satisfied the CWA and EPA regulations. EPA does not expect New Mexico to adopt uses for ephemeral or intermittent waters that cannot be attained, but in those instances, 40 CFR 131.10(j)(1) requires the State to submit a use attainability analysis (U
