Better Assessment Science Integrating point & Non-point Sources (BASINS)

BASINS (Better Assessment Science Integrating point and Non-point Sources) is a multipurpose environmental analysis system designed by the U.S. Environmental Protection Agency to help regions, states, and local agencies develop cost-effective approaches to watershed management and environmental protection.

BASINS integrates a geographical information system, national watershed data, and state-of-the-art environmental assessment and modeling tools. BASINS also includes a Climate Assessment Tool (CAT) that allows users to explore the effects of climate change on streamflow and water quality. 

BASINS is a valuable tool for watershed and water quality-based analysis, including developing total maximum daily load (TMDL) allocations. BASINS runs on non-proprietary, open source, free geographic information system (GIS) software, making the tool universally available to anyone interested in the system. The EPA includes a series of lectures and exercises teaching users how to use BASINS on the website under the "user information and guidance" tab. 


If you have any trouble accessing the website link above, please find here an archived page. You may find this has limited use. 

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  • Modeling tool
  • Tool (general)


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