Lake Mead, the reservoir for drinking water in Las Vegas, is in trouble. The city and its suburbs have long been challenged by a limited water supply, but the very real effects of climate change are exacerbating and accelerating already dry conditions. The region's 2 million residents depend almost entirely on the Colorado River, yet its lake-stored flows are set to dwindle significantly in the next few decades.

Located about 30 miles from the city's downtown, Lake Mead's depth has sunk to perilously low levels— to around 1,080 ft now from about 1,200 ft in 2000.

"It only takes a 10% reduction to cause really big problems," says Tim Barnett, marine research physicist emeritus at the Scripps Institution of Oceanography, San Diego. "We are seeing what we thought we would see when we calculated the impacts of global warming."

As a result, the Southern Nevada Water Authority (SNWA) and a team of engineers and contractors are nearing completion of a $817-million water intake and tunneling project that will enable the regional water agency to draw added supply from the lake's very lowest level. The project will ensure that Las Vegas residents continue to have a stable source of water through the end of this century, SNWA says.

Additionally, the agency expects to submit to its board for approval on May 21 a $650-million construction services contract with a joint-venture team of MWH Global and CH2M. MWH-CH2M will build a new pumping station near the new intake and  implement more stringent conservation measures.

The Drought Cometh

According to those who have studied the river basin's climatological future, the region could get even drier.

For more than 80 years, the Las Vegas area has benefitted from the Lake Mead reservoir, created in the 1930s by the construction of the Boulder Dam, one of the largest engineering marvels of the past century. Demand on the reservoir was manageable, until the area's population exceeded 1 million in the early 2000s.

In the past decade, as climate modeling became more accurate, stakeholders in the Colorado River basin—including Colorado, Utah, Arizona, Nevada, California and New Mexico—sought better predictions of the waterway's flows.

Barnett performed some of the earliest studies and analyses on historical and future Colorado River flows and lake impacts. By 2009, the results of his research were published and peer-reviewed by the National Academy of Sciences. The predictions refuted previously held assumptions. The study predicted declines in snowpack and warned of changes in other trends that had been temporarily increasing the amount of water available to western states since 1906.