These data sets are complete digital hydrologic unit boundary layers for the Desert Landscape Conservation Cooperative. These data sets consist of geo-referenced digital data and associated attributes created in accordance with the "FGDC Proposal, Version 2.0 - Federal Standards For Delineation of Hydrologic Unit Boundaries 3/01/02"(http://www.ftw.nrcs.usda.gov/huc_data.html), and amended with the Federal Standards For Delineation of Hydrologic Unit Boundaries; Version 2.0 October 1, 2004. Polygons are attributed with hydrologic unit codes (HUCs), names, sizes, downstream hydrologic units, types of watersheds, non-contributing areas and flow modifications. Lines are attributed with the highest hydrologic unit code for each watershed, linesource and a metadata reference file.
HUC is the acronym for Hydrologic Unit Code (HUC). Every hydrologic unit is identified by a unique HUC consisting of 2 to 12 digits based on the levels of classification in the hydrologic unit system. A hydrologic unit describes the area of land upstream from a specific point on the stream (generally the mouth or outlet) that contributes surface water runoff directly to this outlet point. Another term for this concept is drainage area. (HUC Primer, http://www.mowin.org/pdf/hucprimer.pdf, accessed 29 July 2015).
