Work on Lake Mead water intake leaves valley down to its final straw

Nobody panic, but for the next five months or so our entire water supply will depend on a single pipe and pump station at Lake Mead.

The Southern Nevada Water Authority has shut down one of the two intake pipes used to deliver water from the lake to every home and business in the Las Vegas Valley and Boulder City.

Intake No. 1 was taken offline early this month so workers can connect it to the pump station for Intake No. 2 and, eventually, a new third intake now under construction at the lake.

Until that connection has been made, most likely by the end of March, all of the valley’s water will come from Intake No. 2.

Marc Jensen, director of engineering for the water authority, delivered the news to authority board members Thursday during a discussion of the so-called third intake project at Lake Mead.

After some asked questions about cost, the board unanimously approved a 13-month extension of the completion date for the new $817 million intake, which is now scheduled to be finished by July 4, 2015.

Thursday’s vote to give third-intake general contractor Vegas Tunnel Constructors more time did not come with any additional money attached. Water authority General Manager Pat Mulroy had already approved about $13 million from a contingency fund to compensate the contractor for the unexpectedly difficult conditions it has encountered 600 feet underground.

To date, Vegas Tunnel Constructors has received about $16 million of the $40 million in contingency money set aside under its $447 million contract with the authority.

Clark County Commissioner Steve Sisolak, who serves on the water authority board, wanted to know whether anyone could guarantee him that this would be last contingency money paid out on the job.

“Of course not,” Jensen said. “There are still potential difficulties ahead.”

“That’s what the contingencies are for,” Mulroy added.

As for the work now ramping up on Intake No. 1, Jensen said it’s always a concern when you rely so heavily on a system that has no real backup. But the chance of something going wrong with Intake No. 2 in the coming months is extremely remote.

Water is drawn through the intake pipe by 22 individual pumping units, each hooked up to a secondary power supply in case the main power goes out. So there’s redundancy, Jensen said.

A cap will be placed temporarily over the opening of Intake No. 1 sometime before the end of the year so the pipe can be drained. Then crews from general contractor Renda Pacific will venture inside to drill and blast a 110-foot vertical shaft from the bottom of the Intake No. 1 pump station down to a connector tunnel they are now finishing 400 feet underground near the shore of Lake Mead.

The $12 million fix was approved in September as an emergency addition to Renda Pacific’s original $52 million contract with the authority. The additional work is expected to extend the life of Intake No. 1, which is the oldest and shallowest of the authority’s straws in the shrinking lake.

Without the work, the intake and its pump station could become inoperable if the surface of Lake Mead drops another 40 to 45 feet from where it is now. The improvements will keep the intake working even if the lake’s surface falls almost 60 feet, effectively buying the authority more time to get the third intake finished.

This certainly won’t be the first time the Las Vegas Valley has survived with just one straw at Lake Mead. The community got by with a single intake and pump station for several decades, but the need for a backup grew as it began to draw more water from the lake and less from the valley’s groundwater.

In the 1990s, before there was an Intake No. 2, an electrical problem shut down the one and only intake and pumping station, cutting off all access to lake water for about three days.

If that should happen again in the next few months, water authority spokesman J.C. Davis said residents can expect to see emergency restrictions on water use.

There is enough water stored in the valley at any one time to keep taps flowing for several days, and additional water can be pumped from the local groundwater table. But some areas would suffer more than others.

In Boulder City where Davis lives, for example, there really isn’t a backup supply or any significant storage. If the system that pulls water from Lake Mead goes down completely, he said, “We’re basically screwed.”

Contact reporter Henry Brean at hbrean@reviewjournal.com or 702-383-0350. Follow him on Twitter @RefriedBrean.