At top of map: 'United States Department of the Interior, Geological Survey. Water-supply paper 1780, plate 1.' At bottom of map: 'Base from Army Map Service sheets NJ 11-9, NJ 11-12, and NI 11-3 (1947).' 'Boundary between bedrock and alluvium in Clark County, Nev., compiled by Ben Boyer, E. H. Pampeyan and C. R. Longwell. In Lincoln and Nye Counties, contact determined from aerial photographs.' 'Interior--Geological Survey, Washington, D.C.--1965--W63358.' Includes township and range lines.Relief shown by contours. Thematic map. Scale 1:250,000 (W 116°--W 114°45´/N 37°00´--N 35°30´). Series: Water-supply paper (Washington, D.C.), 1780. Originally published as plate 1 of Available water supply of the Las Vegas ground-water basin, Nevada, by Glenn T. Malmberg, published by the Geological Survey in 1965 as its Water-supply paper 1780.

This series of photographs documents the historic water overflow at Hoover Dam as seen from the Arizona side of the dam. Taken in August of 1983, this overflow marked the first time the spillways were used during a flood. After initially being filled, the spillways were tested once in August of 1941.