Vegas water watchers raise drought fears

Water supplies to Las Vegas could run dry within six years thanks to receding water levels at Lake Mead, officials warned last week, bringing into question the long-term viability of the fastest growing city in the US.

Pat Mulroy, the chief executive of the Southern Nevada Water Authority, said that the water level is due to drop below the inlets for the two "straws" that currently deliver water from the lake to the desert city.

Mulroy, testifying before the state legislature, pointed to an $817m (£573m) project to create a third pipe as the best means of maintaining the city's water supply. This 2.5-mile underground pipe is designed to create an inlet much deeper in the lake than its predecessors.

Over the past nine years, the Colorado river, which feeds Lake Meade, has experienced an average inflow two-thirds of its normal intake, Mulroy said in his presentation.

In January 2000, its levels were at 1,225ft. Now, they are down to 1,112ft. Although the city has cut its water consumption by 21 billion gallons a year since 2002 as a result of water saving measures, water levels in the lake have been continuing to decrease thanks to long-term drought in the region.

Should recent conditions continue, water levels will drop below the first pipe's inlet in 2013, the presentation said, while flow through the second pipe could be cut off by 2015. The date for the third pipe is scheduled to be completed by 2013, just in time to avoid serious disruption to water supplies.

"The idea is that right now, it's going to be just in time," said Scott Huntley. "The options that we have [if the third pipe is not ready] are enforced mandatory conservation, and increasing the pumping capacity on the existing intake – running it harder."

The problem for the SNWA is that its revenues have plummeted over the last couple of years, thanks primarily to a drop in the housing market. Charges to connect new housing developments to the water grid, which account for 57 per cent of its revenue, peaked at $118bn in 2006. They are expected to provide just $18bn this year.

In the longer term, the authority is hoping to get a permit for a $3.5bn project that would siphon groundwater from Eastern Nevada, reducing the city's reliance on the Lake to supply 90 per cent of its water to around 60 per cent.

But scientists remain fearful that in the long term the desert city will have to find alternative water supplies and may even become unviable.

A number of official government reports have warned climate change will result in severe water shortages in the south west of the country, while a study by The Scripps Institution of Oceanography recently predicted Lake Mead could be dry by 2021 if conditions do not improve. There is also a 50 per cent chance that water levels could be too low to generate hydroelectricity by 2017, said the institution's report.