Water Quality Control Commission Unanimously Approves Mine’s Proposed Regulatory Amendments to Surface Water Standards

On October 8, 2019, following a public hearing, the New Mexico Water Quality Control Commission (WQCC) unanimously approved Peabody Natural Resources Company’s (Peabody) proposed amendments to the WQCC’s regulations governing standards for interstate and intrastate surface waters codified at N.M. Code R. § 20.6.4. The approved amendments reclassify and assign new use designations to portions of San Isidro Arroyo, Mulatto Canyon, Arroyo Tinaja, and Doctor Arroyo including tributaries to these waters. The approved regulatory amendments reclassify these waters as ephemeral, from intermittent or perennial, which changes the highest attainable aquatic life and recreational use for these waters from “marginal warm water aquatic life” and “primary contact” to “limited aquatic life” and “secondary contact.” The WQCC’s proposed regulatory changes are subject to final approval from the U.S. Environmental Protection Agency.

In order to demonstrate the stream segments are unable to attain their currently designated use due to natural, ephemeral low flow conditions that prevent the attainment of the use, Peabody conducted a use attainability analysis (UAA), as required and in accordance with 40 C.F.R. § 131.10(g) and N.M. Code R. § The UAA implemented the New Mexico Environment Department’s (NMED) approved hydrology protocol (HP) to support its findings.

Peabody is the first third party to conduct a UAA and implement NMED’s HP to reclassify stream segments within New Mexico. The WQCC complimented Peabody on working with NMED, and for its clear and thorough presentation of evidence and above-and-beyond approach to applying the HP for the watersheds analyzed.

Peabody’s proposed regulatory amendments based on its UAA are likely the first of many to come, given the number of ephemeral streams in New Mexico that are currently classified as intermittent or perennial with the highest attainable aquatic life and recreational use for these waters as warm water aquatic life and primary contact.

Editor’s Note: The reporter represented Peabody in this matter.

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