Implementing the 2018 Recommended Aquatic Life Water Quality Criteria for Aluminum: U.S. Environmental Protection Agency Draft Technical Support Document

The United States Environmental Protection Agency (“EPA”) issued a Draft Technical Support Document titled:

Implementing the 2018 Recommended Aquatic Life Water Quality Criteria for Aluminum (“Draft Document”)

See EPA-823-D-19-001 (July 2019).

EPA’s purpose in issuing the Draft Document is to assist states and authorized tribes in implementing the agency’s Recommended Final Aquatic Life Ambient Water Quality Criteria for Aluminum.

Water Quality Criteria (“WQC”) are ambient water quality conditions that are deemed protective of the uses established for a waterbody. States are required by the Clean Water Act to adopt WQC protective of the designated uses. The WQC must specify the maximum concentration of pollutants that may be present in the water without impairing its suitability for certain uses. They generally assume three forms.

1. Numerical terms reflecting maximum concentration of a particular pollutant in the receiving water
2. Bioassay or biomonitoring results which reflect mortality rates of certain waterborne organisms relative to the concentrations of particular pollutants
3. Terms narrative in nature

EPA develops WQC pursuant to Section 304 of the Clean Water Act. They are frequently used by the states in establishing or revising their water quality standards. However, states are free to adopt or develop their own WQC if there is a scientific basis for doing so. Such state developed WQC are reviewed and approved by EPA.

EPA notes in the Draft Document that the National 304(a) recommended aluminum criteria are water-chemistry dependent. It further states the criteria values will vary from site to site based on the values of water chemistry parameters at the site. A two-step performance based process is described.

The Draft Document is intended to provide additional insight into this process and related issues.

The Draft Document contains four sections which address:

1. What flexibility does a state or authorized tribe have when adopting the EPA’s recommended aluminum criteria into its water quality standards, and what are the advantages and potential challenges of each approach?
2. How often and over what time period should a state or authorized tribe collect input parameter data? What if DOC data are insufficient?
3. What methods can be used to reconcile model outputs and derive criteria values that will result in protection of aquatic life at a site?
4. How can a state or authorized tribe implement the aluminum criteria in its Clean Water Act programs?

A copy of the Draft Document can be downloaded here.