Hoover Dam Hoover Dam by Ansel Adams, 1942 Official name Hoover Dam Location Clark County, Nevada / Mohave County, Arizona, U.S. Purpose Power, flood control, water storage, regulation, recreation Status In use Construction began 1931 Opening date 1936 Construction cost $49 million (1931) $700 million (2017) Owner (s) United States Government Operator (s) U.S. Bureau of Reclamation Dam and spillways Type of dam Concrete gravity - arch Impounds Colorado River Height 726.4 ft (221.4 m) Length 1,244 ft (379 m) Elevation at crest 1,232 ft (376 m) Width (crest) 45 ft (14 m) Width (base) 660 ft (200 m) Dam volume 3,250,000 cu yd (2,480,000 m) Spillway type 2 controlled drum-gate Spillway capacity 400,000 cu ft / s (11,000 m / s) Reservoir Creates Lake Mead Total capacity 28,537,000 acre ft (35.200 km) Active capacity 15,853,000 acre ft (19.554 km) Inactive capacity 10,024,000 acre ft (12.364 km) Catchment area 167,800 sq mi (435,000 km) Surface area 247 sq mi (640 km) Maximum length 112 mi (180 km) Maximum water depth 590 ft (180 m) Normal elevation 1,219 ft (372 m) Power Station Operator (s) U.S. Bureau of Reclamation Commission date 1936 -- 1960 Hydraulic head 590 ft (180 m) (Max) Turbines 13 × 130 MW 2 × 127 MW 1 × 68.5 MW 1 × 61.5 MW Francis - type 2 × 2.4 MW Pelton - type Installed capacity 2,080 MW Capacity factor 23 % Annual generation 4.2 TWh (15 PJ) Website Bureau of Reclamation: Lower Colorado Region - Hoover Dam Hoover Dam U.S. National Register of Historic Places U.S. National Historic Landmark Show map of USA West Show map of the US Show all Nearest city Boulder City, Nevada Coordinates 36 ° 0 ′ 56 '' N 114 ° 44 ′ 16 '' W ﻿ / ﻿ 36.01556 ° N 114.73778 ° W ﻿ / 36.01556; - 114.73778 Coordinates: 36 ° 0 ′ 56 '' N 114 ° 44 ′ 16 '' W ﻿ / ﻿ 36.01556 ° N 114.73778 ° W ﻿ / 36.01556; - 114.73778 Built 1933 Architect Six Companies, Inc. (structural), Gordon Kaufmann (exteriors) Architectural style Art Deco MPS Vehicular Bridges in Arizona MPS (AD) NRHP reference # 81000382 Significant dates Added to NRHP April 8, 1981 Designated NHL August 20, 1985
when did the hoover dam started being built
1931 1931