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Lake Mead bathtub ring

Lake Mead

The Colorado River pools behind Hoover Dam to create Lake Mead, the largest reservoir in the United States.

The lake is the source of nearly 90 percent of Southern Nevada's water, and it is under constant scrutiny to ensure the quality of the water.

The Nevada Division of Environmental Protection established the Lake Mead Water Quality Forum to protect public health and preserve the water quality of the Las Vegas Wash, Las Vegas Bay, and Lake Mead.

Thermal stratification

During warmer months, the lake's top portion of water heats up faster than the deeper portions, causing a distinct layering of water, or thermal stratification. Separating warm and cold water, thermal stratification protects the deeper layer of water by forming a natural barrier that keeps organisms and pollution near the surface. Located at the same depth as the intakes, the deeper layer of water also is of better quality.

Destratification—the breakdown of these layers as the water becomes isothermic, or one temperature throughout—can occur in the winter, increasing the possibility of pollutants traveling near the intakes.

Lower Colorado River water quality monitoring

The Lower Colorado River Regional Water Quality Database contains more than 2 million records covering nearly 1,000 parameters including depth, temperature, pH, conductivity, dissolved oxygen, nutrients, metals, and organics.

Information in the database is provided by SNWA, City of Las Vegas, Clark County Water Reclamation District, UNLV, Bureau of Reclamation Denver, Bureau of Reclamation Lower Colorado River, City of Henderson, Metropolitan Water District of Southern California, Clark County Regional Flood Control District, Colorado River Regional Sewer Coalition, Central Arizona Project, and Nevada Division of Environmental Protection.

Email us for access to the Lower Colorado River Regional Water Quality Database.

employee conducting water sampling from side of boat at Lake Mead

Water samples are drawn from the lake every week to determine if there is a presence of fecal coliforms, E. coli, and perchlorate. The tests also determine the level of:

  • Dissolved oxygen
  • pH level
  • Conductivity
  • Temperature and turbidity
  • Nutrients