'Bathtub ring' on Hoover Dam shows level of Lake Mead dropping even further amid continuing drought in America's west

• Lake Mead already at lowest point since it began being filled in 1930s
• But that is expected to drop by another 10ft by the end of this summer
• Drought across western states means demand is outstripping supply
• Vegas authorities have just completed third pipeline to draw from it  

By Chris Pleasance for MailOnline

Published: 05:41 EST, 6 July 2015 | Updated: 07:45 EST, 6 July 2015

Visible at the top of the Hoover Dam, this 'bathtub ring' shows the devastating effects of a drought which has seen the level of Lake Mead drop to an historic low.

The lake's surface now sits at just over 1,000ft, the lowest point it has been since it started being filled in the early 1930s when the dam was finished.

The water level is so low that officials from Las Vegas, which draws its water from Lake Mead, have been forced to spend $800million building a third pipe to ensure their supply does not run out.

The pipe is needed because the top of the lake will soon dip below the height of the first two pipelines, leaving them out of the water.

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Time is running out: A dramatic 'bathtub ring' mark is visible on the Hoover Dam as the level of Lake Mead continues to drop below historic low amid drought in the west

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Stark: Since its high in 1983, the level of Lake Mead has dropped 140ft, leaving a white ring mark around its shores, as the surface is expected to drop another 10ft by the end of the summer

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Desperate: Lake Mead is now at its lowest level since the artificial body of water began being filled in the early 1930s after the Hoover Dam (pictured) was finished

Lake Mead is currently using just 40 per cent of its total capacity, while the surface has been dropping for 15 years as demand has far outstripped the amount of water flowing into it.

The artificial body of water, created by the Dam, is largely filled by meltwater from the Rocky mountains, which have seen smaller than average snowfall for more than a century.

A dramatic ring has become more and more visible on the cliffs around the lake in recent years, as the level has dropped by almost 140ft, the equivalent of a 20-storey building.

As well as Vegas, large parts of California and Arizona also rely on water from the lake to supply farms and homes, and the ongoing drought there has put added pressure on supplies.

Nevada's Lake Mead hit an all-time low last year

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Emptying: The lake is refilled mostly by meltwater from the Rocky mountains, but these have experienced low snowfall for the last 15 years which has failed to replace the water taken out

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Drying up: Las Vegas draws almost 90 per cent of its water from Lake Mead, with California, Arizona and parts of Mexico also using it as a source

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Disappearing: The levels in the lake are now teetering on the point where an official shortage would be triggered, as officials are agreed that further action is needed

It means the rate of decline is now speeding up, and the lake expected to drop by another 10ft by the end of the summer. 

The ring on the Hoover Dam shows how much the lake surface has dropped in recent months. 

While the people that draw from the lake have agreed to cut down on their usage, with Vegas dropping its consumption by 30 per cent in a decade, officials agree that more action is needed.

Speaking to NPR in April, Kumud Acharya, from the University of Nevada's Desert Research Institute, said: 'When we don't have water, these utilities have to find water, bring that water from somewhere.

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Last ditch: Authorities in Las Vegas have been forced to spend more than $800million drilling a third pipeline to draw water from the lake

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Nothing left: The surface of Lake Mead is about to drop below the level of Vegas's other two pipelines, meaning a third - deeper down in the lake - was needed to stop the city drying up

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Draining: Despite expanding, Vegas has managed to cut its water consumption by 30 per cent over the last decade, but more action is needed as the level of Lake Mead continues to drop

'Whether it's a desalinization project or whether it's from groundwater pumping from somewhere else, the cost is going to go up. We just have to pay more.'

While the problem is well recognised, the lake is currently just above the level which would trigger an official water shortage.

However, according to AZ Central, that may well be reached by this time next summer, though nobody can be certain until after winter when the lake refills.