Polygon layer representing all watershed Boundaries for the Implementation Watersheds, including Approved, In Progress and Completed Implementation Areas.

Polygon feature class outlining the major river basin watershed areas within Virginia.

This dataset depicts TMDL watershed boundaries. A TMDL watershed is the area covered by a TMDL equation. It consists of one or more impaired streams that have an assigned Cause...

This data is the latest (Version 6) national hydrologic unit (HU) boundaries at levels 1-6 for Virginia developed and maintained by the Virginia Department of Conservation and...

From the site: "This statewide watershed coverage (12 digit HUC) was provided by the Natural Resources Conservation Service (NRCS). The coverage is in ArcView shapefile format...

A listing of links for downloading GIS data regarding Fairfax County VA; of particular interest are the downloadable census/geography, soils, and water files.