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.
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.
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.