The stormwater structures data is comprised of points (inlets, manholes, pipe ends, culvert ends, and control devices). The pipe and culvert point structures, typically one at each end of the pipe/culvert line, include the stormwater infrastructure where there is a change in pipe direction. The data was collected primarily in eastern Loudoun in the more urbanized areas of the County. The data was collected in the field using GPS so that at least 95% of data is accurate to less than 3.28 ft. (1 m).

The stormwater pipes and culverts data is comprised of lines. The pipes and culverts are the man-made structures composed of concrete, metal and plastic used to convey stormwater from catch basins and ponds to the natural drainage ways and swales that eventually discharge to creeks and streams. The pipes and culverts data was collected primarily in eastern Loudoun in the more urbanized portions of the County and was collected in the field using GPS instrumentation. At least 95% of the locational data for the pipes and culverts is accurate to within 1 meter or less. Pipes and culverts are named and digitized in the direction of water flow.