What is the role of the Hoover Dam?

The facility provides enough power for 8m people across Nevada, Arizona and California

The Hoover Dam is one of the most famous pieces of civil engineering in the United States, and is a major tourist attraction as well as an essential power source for much of the West.

The dam created and impounds Lake Mead, which when full in non-drought years is the largest reservoir in the US, and its generators provide power for public and private utilities in Nevada, Arizona, and California.

Each year the dam generates 4.5bn kilowatt-hours of hydroelectric power for use in the three states, enough to serve around 8m people in the region.

The Bureau of Reclamation says that during peak electricity periods, enough water runs through the generators to fill 15 average-sized swimming pools – 20,000 gallons each – in one second.

When operating at full capacity generators at the hydropower site can supply all the electricity needed by a city of 750,000 people.

Hoover Dam was constructed in Black Canyon of the Colorado River on the border between Arizona and Nevada.

It was built and is operated by the Department of the Interior’s Bureau of Reclamation. Building work began in 1931, with the dam and power plant completed in 1936.

The dam measures 726.4 ft in height above bedrock, the size of a 60-storey building. The base of the dam is 660ft thick, the size of two football pitches.

The main purpose of the dam is to control the Colorado River during flooding periods to prevent damage to the region below it. During non-drought periods, the dam and Lake Mead store the Colorado River’s runoff, providing water to irrigate hundreds of thousands of acres of land in Southern California and Arizona.

But the climate crisis has seen Lake Mead lose water at a dramatic rate during the multi-year drought, which has seen states that rely on its supply see cuts.

The latest report from the US Bureau of Reclamation stated that Lake Mead was just over 1,040 feet above sea level in July. It has dropped nearly 10 feet in the past two months and is currently at just 27 per cent of its maximum capacity.