Lake Mead water level plunges to historic low

17 August 2021

Created in the 1930s by the completion of the Hoover Dam blocking the Colorado River, Lake Mead has contracted to a historically diminished area, threatening the way of life of millions living in the West and Southwest US who depend on it for water.

For the first time ever, officials have declared a water shortage which has triggered cuts in supply to parts of the already drought-stricken Southwest. The governor of Utah has implored people to pray for rain.

And it is all mainly down to a planet that is overheating. The largest reservoir in the US has fallen victim to the consequences of climate change, but also to rampant human water consumption: record low rainfall and a two decade-long drought; soaring temperatures and higher evaporation levels: rapidly expanding populations; excessive water usage from Los Angeles to Phoenix; and a declining mountain snowpack which typically sees the Colorado replenished by melting snows have all contributed to a much-reduced Colorado River flow. According to the US Geological Survey, the river’s flow has declined by around 20% over the past century.

These factors have caused the lake to drain at an alarming rate: with a water level at 325m above mean sea level, the lake is only 35% full and at its lowest level since its creation in 1935. The results are alarming: marinas and boat launch ramps have either had to be relocated or extended to reach the water line, and buoys which once warned of hazards now languish on dry land. If water levels continue to fall, one of the two original water intakes could be rendered obsolete.

For at least the past two decades, these dangers have been heeded, hence the completion in 2015 of Southern Nevada Water Authority’s ambitious Third Intake project. Constructed over a seven-year period, a 7.2m-diameter, 4.5km tunnel was bored beneath the lake under hyperbaric pressures as high as 15bar to convey water from the new intake located at the lake’s bottom. Designed to ensure continuity of water supply for millions in the southwest, the tunnel and intake will continue to ensure supply amid ongoing falls in the lake’s level.

As the drought continues, and a water shortage is officially declared for the first time ever at the lake by the Bureau of Reclamation, mandatory water restrictions look set to be instigated for Arizona, Nevada and Mexico starting in 2022.