This dataset includes hydrographic flowlines (streams/rivers, pipelines,
connectors, canals/ditches, coastlines, underground conduits, and other
artificial paths) within the Lower Colorado region. This corresponds to
region 15 (HUC level 2) in the national Watershed Boundary Dataset
(WBD). This is an extract of the National Hydrography Dataset (NHD) -
medium resolution (1:100,000 scale). For further information on the NHD
dataset, see
http://nhd.usgs.gov/