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Southern Nevada Water Authority

Lake Mead

Lake Mead is the largest reservoir in the US

Lake Mead is the largest reservoir in the
United States.

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.

Organisms living in the lake can contribute to taste and odor problems in the finished drinking water supply. These organisms also can clog the Southern Nevada Water Authority (SNWA) water treatment filters.

Lake Mead Monitoring and Tests

Water samples are drawn from the lake every week to run tests 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

Thermal Stratification

Throughout the year, Las Vegas Valley Water District (LVVWD) personnel closely monitor the lake for the possibility of destratification.

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.

When the lake cools down in the winter, destratification can occur--the break down of these layers as the water becomes isothermic, or one temperature throughout. This can increase 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 different parameter 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 and the Colorado River Regional Sewer Coalition. In addition, there are plans to add data from the Central Arizona Project and Nevada Division of Environmental Protection.

For access to the database, fill out the Water Quality Database Interest Form.

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