Tools to Enhance the NPDES Program
- Search for NPDES Permitted Facilities
- Tools to Enhance the NPDES Program
- Data and Mapping Tools
More frequent and intense storm events, floods, droughts, storm surges, sea level rise, and altered waterbody temperatures and flows are occurring across the United States. These changes and the accompanying impacts to water quality can adversely impact communities and the water infrastructure on which they rely. For example, alterations in precipitation patterns and flooding due to intense storms and sea level rise are changing what is needed for permitted systems to continue to operate and maintain their control systems. The resources below have been adapted to help National Pollutant Discharge Elimination System (NPDES) permits protect water quality and critical infrastructure under these changing conditions.
Thermal Discharges in NPDES Permits: Overview of Resources and Tools
EPA's Thermal Discharges in NPDES Permits: Overview of Resources and Tools (pdf) compiles existing information on thermal discharges, warming surface waters, unpredictable precipitation and stream flow, drought conditions for biological resources, thermal mixing models, monitoring equipment, impacts on biota, and relevant case studies for permitting and managing thermal discharges subject to Clean Water Act requirements.
Low Flow Statistics Tools – A How-To Handbook for NPDES Permit Writers
EPA's Low Flow Statistics Tools – A How-To Handbook for NPDES Permit Writers (2023) describes how to estimate low flow statistic values in a variety of situations using free publicly available tools, as well as best practices to ensure low flows are reasonably representative of current conditions. NPDES permit writers often need to calculate low flow statistics for reasonable potential analyses and water quality-based effluent limitation (WQBEL) calculations or to confirm estimates provided by the permittee during the NPDES permit development process.
NPDES Permit Writers’ Clearinghouse
EPA's NPDES Permit Writers' Clearinghouse contains links to permit language, templates, and other resources that are shared by permit writers in the NPDES program.
Green Infrastructure
Incorporating green infrastructure on multiple scales throughout a community and watershed provides cleaner air and water, as well as significant value for the community with flood protection, varied habitat, and beautiful green spaces. As different parts of the country become drier, wetter, or hotter, green infrastructure can help strengthen communities (e.g., manage flooding, prepare for drought, reduce urban heat island effect, lower building and water management energy demands, and protecting coastal areas). Learn more about how communities can use green infrastructure to address Clean Water Act requirements.
Long-term Planning
These long-term planning resources and case studies can be an effective way to prioritize projects to meet water quality standards for a more robust infrastructure and community:
EPA-USGS Technical Report: Protecting Aquatic Life from Effects of Hydrologic Alteration
An EPA-USGS technical report, Protecting Aquatic Life from Effects of Hydrologic Alteration (pdf) (2.41 MB), describes the effects of flow alteration on aquatic life designated uses in streams, rivers, and other natural flowing water bodies; shows how Clean Water Act mechanisms address hydrology or flow alterations through state and tribal examples, and provides a flexible, nonprescriptive framework to quantify flow targets to protect aquatic life from the effects associated with flow alteration.