Groundwater is an important resource.
About 10 percent of the Las Vegas Valley's water comes from groundwater, which is a water supply under the Earth's surface. In some areas, water fills the spaces throughout porous bedrock, alluvial gravels, sands, silts and clays to form a natural reservoir.
Groundwater occurs as part of the hydrologic cycle, which is the movement of water between the earth and the atmosphere through evaporation and precipitation. The underground area where groundwater exists is referred to as an aquifer.
Groundwater comes from three major aquifer zones (underground rock or sediment that is permeable and can conduct water) generally situated from 300 to 1,500 feet below land surface. This drinking-water supply is protected from surface contamination by a layer of clay and fine-grained sediments throughout most of the Las Vegas Valley.
Occasionally, news reports mention that contaminants such as pesticides and fertilizers have been found in groundwater. These reports typically refer to water in the shallow groundwater system, water that occurs within 50 feet of land surface. It is separated from the primary producing aquifers by thick layers of clay and fine-grained sediments. This water is not used for drinking water.
Residents using community and domestic wells rely on groundwater 100 percent of the time to meet their water needs. There are approximately 6,700 wells within the Las Vegas Valley that provide groundwater year-round to residents and other users who aren't on a municipal water supply.
The Water District pumps groundwater from wells to meet peak summer demand. During the hot summer months from May through September, groundwater can account for up to 39 percent of the valley's daily water supplies.
Visit LasVegasGMP.org for more details about groundwater in the Las Vegas Valley.