Jump to main content or area navigation.

Contact Us

Water: Water Quality Standards Academy

Introduction: EPA Role in Developing Aquatic Life Criteria

Aquatic Life Criteria

« Page 2 of 20 »

Basic Course: Supplemental Topics

Section 304(a)(1) of the Clean Water Act (CWA) requires EPA to develop and publish—and to periodically review and revise as necessary—nationally recommended criteria for water quality that accurately reflect the latest scientific knowledge. The criteria are based solely on data and scientific determinations about the relationship between environmental concentrations of a pollutant and its effects on, for instance, aquatic life. Thus, EPA criteria development does not involve consideration of social and economic impacts or the technological feasibility of not exceeding the chemical concentration values in ambient water.

Key Point. EPA’s nationally recommended water quality criteria provide guidance to States and Tribes for developing numerical and narrative criteria for their water quality standards in support of the CWA. They also provide guidance for the Agency itself when promulgating Federal regulations under the CWA.

The majority of EPA’s currently recommended aquatic life criteria were derived using the methods outlined in EPA’s ALC guidelines published in 1985.

Resource. EPA’s 1985 Guidelines for Deriving Numerical National Water Quality Criteria for the Protection of Aquatic Organisms and Their Use (PDF) (104 pp, 3.3MB, About PDF).
Resource. Links to both finalized aquatic life criteria and those that are under development (along with other ALC resources) are provided on EPA’s ALC web page.

Since publication of the ALC derivation method, important scientific advancements have been made in aquatic toxicology and biology; fate, transport, and effects modeling; and ecological risk assessment. In addition, water quality impairment issues have become increasingly complex. Given these developments, EPA has been leading an effort to update the ALC derivation guidelines.

Resource.EPA’s Draft Strategy: Proposed Revisions to the “Guidelines for Deriving Numerical National Water Quality Criteria for the Protection of Aquatic Organisms and Their Uses” (February 6, 2003) (PDF) (5 pp., 74K, About PDF).
Learn More. A somewhat recent area of interest related to modifying the 1985 guidelines focuses on so-called contaminants of emerging concern (CECs). Proceed to the Learn More Topic. » (Note: This link launches a pop-up window.)

For informational purposes only–Not official statements of EPA policy.

« Previous Next »

Jump to main content.