This website provides tools and data for comparing watershed characteristics within user-selected geographic areas anywhere in the conterminous United States. The content in this site is technical and intended for scientific audiences.

The Watershed Index Online (WSIO) is a free, publicly available data library of watershed indicators and a decision-support tool.  It was developed by EPA to assist resource managers, citizens, and other users with comparing and prioritizing watersheds. In this site users can find:

• WSIO Tool - a customized MS Excel Workbook that calculates indices, compares watersheds and produces results in rank-ordered tables, graphs and maps;
• WSI Indicator Library - measurements of ecological, stressor, and social characteristics compiled for roughly 83,000 small (HUC12 scale) watersheds across the conterminous United States;
• WSIO User Support - General and specific directions on how to open the WSIO Tool online, select a geographic area, choose indicators, do comparative watershed assessments, and save the analyses.