EPA bases aquatic life criteria on how much of a chemical can be present in surface water before it is likely to harm plant and animal life. EPA designs aquatic life criteria to protect both freshwater and saltwater organisms from short-term and long-term exposure.

• Final EPA-USGS Technical Report: Protecting Aquatic Life from Effects of Hydrologic Alteration
• Aquatic Life Ocean Acidification and Marine pH
• White Paper: A Summary of the Literature on the Chemical Toxicity of Plastics Pollution on Aquatic Life and Aquatic-Dependent Wildlife
• Historical Water Quality Criteria Documents

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.

• Fact Sheet: Final EPA-USGS Technical Report: Protecting Aquatic Life from Effects of Hydrologic Alteration
• Federal Register Notice: Final EPA-USGS Technical Report: Protecting Aquatic Life from Effects of Hydrologic Alteration (December 21, 2016)
• Document: Final EPA-USGS Technical Report: Protecting Aquatic Life from Effects of Hydrologic Alteration
• Response to Public Comment: Final EPA-USGS Technical Report: Protecting Aquatic Life from Effects of Hydrologic Alteration
• Response to Peer Review Comments: Final EPA-USGS Technical Report: Protecting Aquatic Life from Effects of Hydrologic Alteration
• View public comments and other supporting documents on regulations.gov by searching for Docket Number 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.

• Petition for Additional Water Quality Criteria and Guidance Under Section 304 of the Clean Water Act, 33 U.S.C. § 1314, To Address Ocean Acidification
• 2013 Interim EPA response to Petition for Additional Water Quality Criteria and Guidance Under Section 304 of the Clean Water Act, 33 U.S.C. § 1314, To Address Ocean Acidification
• 2016 Final EPA response to Petition for Additional Water Quality Criteria and Guidance Under Section 304 of the Clean Water Act, 33 U.S.C. § 1314, 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.

• Letter on Marine pH Criteria: EPA to Center for Biological Diversity
• Fact Sheet: Ocean Acidification and Marine pH Water Quality Criteria
• Federal Register Notice: Ocean Acidification and Marine pH Water Quality Criteria

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.

• Fact Sheet: A Summary of the Literature on the Chemical Toxicity of Plastics Pollution on Aquatic Life and Aquatic-Dependent Wildlife (December 2016)
• Document: A Summary of the Literature on the Chemical Toxicity of Plastics Pollution on Aquatic Life and Aquatic-Dependent Wildlife

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