‘Second straw’ to allow full share of water

Sunday, Jan. 9, 2000 | 8:51 a.m.

A giant "second straw" will allow thirsty Las Vegas to start slurping up its full share of Colorado River water later this month, but even that healthy extra serving might not be enough to quench the area's future demands.

For water managers, the pipeline is just one step in an intricate dance that must balance growing demands, man-made laws and nature's whims. It's all about watering the desert.

The new $500 million, 4-mile-long pipeline, blasted into the granite of the River Mountains over the past four years, will give Southern Nevada the capacity to siphon off its full share of 300,000 acre-feet of river water for the first time.

The current pipeline only has been able to handle a maximum of 253,000 acre-feet during a single year. The new pipeline will not only make room for the additional 47,000 acre feet, but it also will allow for future growth.

And it's not just Las Vegas' runaway growth that is tapping out the water barrel. The threat of drought poses an even bigger concern for Southern Nevada's future.

The bottom line, according to Southern Nevada Water Authority General Manager Pat Mulroy, is that in an extended drought, Southern Nevada won't be able to suck up a drop more than its share of the Colorado. And that reality has already forced the Las Vegas Valley to start finding secondary water supplies.

In a drought of more than eight years, Lake Mead's waterline could drop below the intakes of the two pipelines, leaving the area unable to even extract its fair allotment from the river system, Mulroy said.

The intake pipes are located on Saddle Island, about a half mile from the lake shoreline. In a severe drought, the island and pipelines could be left high and dry, as much as 100 feet above the lake's water level, she said.

The last time such a drought hit Southern Nevada was in the mid-1950s, when Las Vegas relied on well water. In that long dry spell, Lake Mead shrunk to historically low levels, leaving behind a white bathtub ring of minerals around the shore.

The lake's level is at historically high levels now, but that's no reason to breathe easy, water experts caution. This year has been dry so far, and already in Southern California water officials are muttering the D-word with worry in their voices.

Nevada is the driest state in the nation, and drought is the norm here, Desert Research Institute climatologist Kelly Redmond said. He points out that the 20th century, the only one for which weather records exist, has actually had some of the wettest seasons in Nevada's history.

Scientists know how unusual the "wet" weather of the past 100 years has been from studying lake sediments, tree rings and pack rat waste. That collective ancient evidence shows that the Southwest has long suffered through severe, extended droughts, Redmond said.

From 600 to 800 years ago the Sierra Nevada range suffered a severe drought that left its mark on California's sequoia trees, Redmond said. Pack rat evidence revealed dry weather in the Great Basin thousands of years ago, and the sediment levels indicated drought as far back as 10,000 years.

"For scientists looking to try and figure out what will happen in the future, how do you define drought in a place like this?" he asked.

The Colorado River has only been tapped for drinking water in the last 50 years, and with the Las Vegas area's spectacular growth, the demands on the river in a normal year are already near its capacity.

In a drought year, when the river volume can fall from a high of 15 million acre-feet to 10 million acre-feet, the river may not be able to provide Nevada its full 300,000 acre feet a year.

Not only is less water available in a drought, but it will cost more to deliver. For every foot Lake Mead drops, Mulroy said, the water authority pays an extra $40,000 per year in power costs to pump the state's share of the river to the Las Vegas Valley.

But Nevada managers are worried about more than just rapid growth and a long drought. They also are keeping an eye on California and an ongoing war over just how much Colorado River water the state can legally suck up.

Nevada is one of six Western states that have been fighting for decades over California's growing reliance on unused water from upstream states.

California was allotted 4.4 million acre-feet a year in the Boulder Canyon Project Act of 1928, but each year it taps water allotments that aren't used by other states. Last year, California slurped up 47,000 acre-feet that went unused by Nevada.

California wants to continue the practice, but other states are growing increasingly protective of their shares, fearing their allotment of the rRiver won't be there when they need it.

The water wrangling will resume this spring, but the fight is expected to continue for years.

Until that disagreement is settled, California will be able to keep drawing more than its share of the river.

As protection against the increasing demands on Colorado River water, the Southern Nevada Water Authority has been quietly laying claim to ground water rights to supplement what it can get from Lake Mead.

And the new pipeline also might help in that effort.

Together, the two pipelines can draw up to 700,000 acre-feet of water, and while the Las Vegas Valley is not entitled to that much out of Lake Mead, it can, with conservation measures, get up to 480,000 acre-feet. Southern Nevada is allowed to draw more water out of the lake if it returns treated reused water to the system. The process, called return flow credits, must use only treated river water and the state has successfully augmented its piece of the water pie in the past.

The excess pipeline capacity was built with the hope that more Colorado River water might become available as the area's demands increased.

The new pipe also provides a critical backup in case the older line, which opened in 1971, needs repairs.

And as part of the massive $2.2 billion expansion project -- paid for with an extra quarter-cent added to the sales tax last April -- Southern Nevada will get a new treatment plant in 2002 that will almost double the amount of water that can be delivered to Las Vegans -- to 700 million gallons a day.

The project also will provide cleaner water. The new pipeline is 50 feet deeper than the original, so if the lake is murky at one level, the water authority can draw at the other level.

In addition, the water district is adding ozone treatment to kill dangerous organisms such as cryptosporidium and giardiases. Forty-three residents died during a 1994 cryptosporidium outbreak in Southern Nevada.

Building the pipeline was an engineering challenge, Water District Deputy General Manager David Donnelly said, as crews had to blast a tunnel uphill through the mountain from Lake Mead to the outskirts of Henderson, where it hooks into the 75 miles of piping and pumps that send water valleywide.

Nevada's water managers don't see the "second straw" as the final answer to the area's water problems, but they are convinced it is a vital step toward making sure the Las Vegas Valley's water needs are met over the next quarter century.