All rivers and streams identified in the 2018 Virginia 305(b)/303(d) Water Quality Assessment. Line work and attributes should not be altered except by the developer (DEQ). This dataset constitutes the United States Environmental Protection Agency (EPA) approved digital version of the assessment hydrology for Virginia. Attributes assigned to each water segment are based on attributes associated with the ID305B (assessment unit ID) entered in the statewide water quality assessment database. QA/QC checks are performed on the database prior to linking attributes to the GIS data, however errors may still occur. Please direct any questions about attribute accuracy to the Data Distributor. The geospatial product is maintained and updated by VA DEQ each assessment cycle (biennially) using the most current NHD product where revisions were made to Virginia waters, the most recent aerial photography provided by the Virginia Geographic Information Network (VGIN), and by freehand digitizing where necessary. Metadata is provided in the data Fact Sheet which contains contact information, process steps, attribute descriptions, and distribution information.