BASINS

BASINS (Better Assessment Science Integrating point & Non-point Sources) bundles the EPA's watershed analysis chain into one system: an open GIS (MapWindow), automatic download of US environmental datasets, watershed delineation, and the venerable HSPF model for continuous simulation of watershed hydrology and pollutant loading, plus links to SWAT and other tools.

HSPF remains one of the most capable continuous watershed water-quality models ever built, and BASINS is its practical delivery vehicle for TMDL and source-assessment work. Development has slowed markedly; it earns its listing for the installed base and the lack of a true replacement.