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 Organisms 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 toxicology 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 Information

Final EPA/USGS Technical Report: Protecting Aquatic Life from Effects of Hydrologic Alteration

Final EPA/USGS Technical Report: Protecting Aquatic Life from Effects of Hydrologic Alteration EPA and the U.S. Geological Survey (USGS) have released a report providing scientific and technical information related to protection of aquatic life from effects of hydrologic alteration. This report presents a literature review of natural flow and a description of the potential effects of flow alteration on aquatic life, as well as examples of water quality criteria that some states have developed to support natural flow and maintain healthy aquatic life. The report also describes a flexible technical and scientific framework that state water managers can consider if they are interested in developing narrative or numeric targets for flow that are protective of aquatic life.

This scientific and technical report is non-regulatory and does not affect or constrain state or tribal discretion.

Hydrologic alteration can include an increase or decrease in water volume, seasonal flow disruption, and dramatic variation in water temperature. Hydrologic alteration can affect aquatic species’ ability to spawn, gather nutrients from the stream system, access high-quality habitat, and more. Hydrologic alteration may be further exacerbated through climate change. Recent climate trends have included the change in frequency and duration of extreme weather events, such as droughts and floods, which can have an impact on flow and affect aquatic life. Maintaining flow targets may help increase a stream’s resilience to climate change by reducing or avoiding intensification of existing stressors.

Previously, the report underwent a public comment period, the draft version of this document can be found in the docket EPA-HQ-OW-2015-0335.

Aquatic Life Ocean Acidification and Marine pH

EPA responded in 2016 declining at this time to take the actions requested in a letter from the Center for Biological Diversity that the Agency develop new water quality criteria or additional guidance under CWA section 304(a) to address ocean acidification.

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.

White Paper: A Summary of the Literature on the Chemical Toxicity of Plastics Pollution on Aquatic Life and Aquatic-Dependent Wildlife

The amount of plastic debris, such as plastic bags and microbeads, entering marine and freshwater environments has increased significantly since the mass-production of plastics began in the 1940s and 1950s. The effect of plastic on aquatic organisms is not well understood beyond the obvious physical impacts. EPA has published a white paper to identify a state of the science on the toxicological effects of plastics and their associated chemicals on aquatic-dependent wildlife and aquatic life and identify opportunities for research to further our understanding of the potential toxic impacts of plastic ingestion throughout the food web.

Request for Nominations of Experts to Augment the Science Advisory Board Ecological Processes and Effects Committee to Provide Advice on Methods for Deriving Water Quality Criteria for the Protection of Aquatic Life

The EPA, SAB Staff Office is requesting public nominations of scientific experts to augment the SAB Ecological Processes and Effects Committee (EPEC) for review of a draft EPA document entitled “Scope and Approach for Revising EPA's Guidelines for Deriving National Water Quality Criteria to Protect Aquatic Life.” The comment period ends September 20, 2016.

Other EPA Publications

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

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