The minimum distance required between a man-made structure and a watercourse. This distance is measured from the top edge of the highest channel bank or the edge of the 100-year flood water surface elevation
The Flood Control District of Maricopa County, Glossary of Flooding Terms, AZ, USA 2009. http://www.fcd.maricopa.gov/Education/glossary.asp x, (ND/ Flood - Amer) {477}