Aquatic Life Ambient Water Quality Criteria

EPA's recommended aquatic life ambient water quality criteria for toxics are levels of a pollutant or other measurable parameter that allows for protection of aquatic life in our nation's waters. Water quality criteria can be numeric (e.g., the maximum pollutant concentration levels permitted in a water body) or narrative (e.g., a criteria that describes the desired conditions of a water body being “free from” certain negative conditions). States, territories and authorized tribes typically adopt both numeric and narrative criteria. These aquatic life criteria are developed under Section 304(a) of the Clean Water Act.

National water quality criteria for the protection of aquatic organisms and their uses:

Guidelines for Deriving Numerical National Water Quality Criteria for the Protection of Aquatic Oranisms and their Uses

EPA's 1985 Guidelines for Deriving Numerical National Water Quality Criteria for the Protection of Aquatic Organisms and Their Uses (the Guidelines) describe a process that uses information form many areas of aquatic toxicoloty to deriving national criteria for the protection of aquatic ecosystems.

EPA Activities Related to Revising the Aquatic Life Guidelines

The existing Guidelines for Deriving Water Quality Criteria for the Protection of Aquatic Life and Their Uses have not been updated since 1985. Although based on science of that time, the past 30 years have witnessed substantial scientific advancement in aquatic toxicology, aquatic biology, fate, transport, and effects modeling, and ecological risk assessment. Such advancements, coupled with increasing complexity of water quality impairment issues requires criteria derivation approaches beyond the existing Guidelines methods.

EPA has begun the process of revising the existing Guidelines used to derive National Ambient Water Quality Criteria for the protection of aquatic life. EPA will consider new and alternative methods for deriving aquatic life criteria to inform revision of EPA’s existing guidance using the newest most appropriate science available.

Common Effects Methodology for Pesticides

EPA's Office of Pesticide Programs (OPP) and the Office of Water (OW) assess the effects of pesticides on aquatic ecosystems using approaches that afford a high degree of protection for aquatic life and that were developed with high quality data using rigorously peer-reviewed assessment methodologies. The Agency anticipates merging these approaches toward a common effects methodology.

Contaminants of Emerging Concern Including Pharmaceuticals and Personal Care Products

It is important for EPA to be able to evaluate the potential impact of contaminants of emerging concern (CECs), including pharmaceuticals and personal care products PPCPs, on aquatic life and have an approach for determining protective levels for aquatic organisms. CECs  and PPCPs are increasingly being detected at low levels in surface water, and there is concern that these compounds may have an impact on aquatic life.

Other Aquatic Life Criteria Information

Aquatic Life Ocean Acidification and Marine pH

EPA published in 2009 a Notice of Data Availability (NODA) to provide interested parties with information that was submitted to EPA regarding ocean acidification and to solicit additional pertinent data or scientific information that may be useful in addressing ocean acidification. Ocean acidification refers to the decrease in the pH of the oceans caused by the uptake of carbon dioxide (CO2) from the atmosphere.

Other EPA Publications

Other EPA publications may be available from the National Service Center for Environmental Publications (NSCEP) free of charge.

Top of Page