View this National Geographic interactive map online to compare today’s low flows with historic Colorado River levels

We’ve seen, heard and gossiped about low flows through the Colorado River, from the designation of the river as ‘endangered’ in April to the Bureau of Reclamation’s Colorado River Water Supply and Demand Study— there’s been a lot of big news on the river recently. Still, Friday’s announcement by the Bureau of Reclamation about the unprecedented alarm on the Colorado has brought new urgency to the slow shrinking of river flows.

The Colorado River’s low flows and shrunken reservoirs– lakes Mead and Powell– have triggered cuts in the amount of water allowed to flow downstream. On Friday, the Bureau of Reclamation announced it would cut water released from Lake Powell’s Glen Canyon Dam by 750,000 acre-feet next year. That’s about enough water to serve 1.5 million homes. This is the first time in the history of the nearly 50-year-old Glen Canyon Dam that downstream water releases will be cut.

During a conference at the University of Colorado Boulder last Friday, Brad Udall used this graph to show basin water levels

“This is like the ‘check engine’ light coming on in your car– it’s a message from the Colorado River telling us that something is wrong and we need to fix it soon,” said Bart Miller, water program director at Western Resource Advocates. “If we don’t take action to fix this ‘Great Depletion,’ we will face serious consequences within a matter of just a few years.” (read more and see Western Resource Advocates (WRA) reaction to the water reduction through their fact sheet)

From the WRA press release: Lake Powell and Lake Mead are the major storage reservoirs for the Colorado River, which provides clean drinking water to 36 million people and powers massive hydroelectric generators at Glen Canyon Dam and Hoover Dam. Water levels at Lake Powell are so low that, under an agreement reached in 2007, it must restrict its release to Lake Mead (the primary reservoir for Lower Basin states) by 750,000 acre-feet – or enough water to meet the residential needs of 7.5 million people. As a result, Arizona and Nevada will likely declare first-ever water shortages by 2015.

Lower releases from Lake Powell mean less water in Lake Mead… and so less water available for Lower Colorado River Basin water users: Arizona, Nevada, Mexico and finally California.

From a National Geographic story:

Las Vegas effectively has two straws into Lake Mead, which is roughly 300 miles (480 kilometers) downstream of Lake Powell, to get its water. One of those straws could stop working once the lake drops too far—somewhere between 1,050 feet (320 meters) and 1,075 feet (328 meters) above sea level, it’s thought. Perhaps as early as autumn 2014, Lake Mead is expected to drop to 1,075 feet (down 25 feet from the current level).

Anticipating trouble earlier, the city’s water authority has been busy installing a third straw to reach a deeper part of Lake Mead.

“It’s essentially a race for us,” Huntley said, as the lake “is going to drop more precipitously than seen in the past.”

If things continue to worsen as climate change brings more evaporation and less rain over time, other issues will come into focus for the seven states and part of Mexico that rely on the Colorado River. Power production at Hoover Dam would stop if the water’s elevation drops enough, for example.

“You won’t be able to put water through the turbines,” Huntley said. “You don’t have enough really to be much more than a river at that point, as opposed to a storage reservoir.”

Southern Nevada Water Authority chief Pat Mulroy told the Las Vegas Review-Journal that she sees this slow-moving drought as an extreme weather event just like Superstorm Sandy was. During her remarks at the University of Colorado Boulder on Friday, Mulroy focused on the need of all basin states to work together, rather than pointing fingers or creating one victim. Mulroy said she has seen the impossible become possible and that we can figure out a way to work through this.

Although Las Vegas may have trouble pulling water from Mead, Arizona will be the first of the Lower Basin states to feel any cuts. Reductions in Colorado River water available to the Central Arizona Project are now 51 percent likely for 2015. The odds of a CAP shortage in 2015 is now 2 percent, and shortage risk will hit 59 percent starting in 2017.  Read more about the possible impacts in Arizona in this Arizona Daily Star article.

The National Geographic story goes on:

Good News, Bad News

The good news is if big snows and rains come in the next year, the feared short-term crisis would be averted—dams could end up delivering normal amounts of water downstream. And even if the dreaded cuts in water do occur, it probably won’t be so bad short term, Udall predicts. That’s because Arizona has been banking water underground.

“There would be a belt-tightening by a small group of water users in Arizona and Nevada, a price increase for a larger group in Arizona…and water use would likely remain constant,” thanks to groundwater pumping, the website CircleofBlue.org reports. At least for a while.

The bad news is if the water shortage drags on for years, people in Nevada, Arizona, and California “would have to answer some very difficult questions,” Udall said.

By current river law, Lake Mead must deliver a certain amount of water downstream, but the lake is draining faster than it’s refilling. At some point, if the situation doesn’t improve, the fear is it may come to deciding this: Do we cut off water supply to Las Vegas to two million people because the reservoir has dropped too low? Or does someone else pay?

“The [logical] answer is you keep supplying water to Las Vegas and you short someone else,” Udall said. But the complicated and often controversial “law of the river” that governs who gets the water from the Colorado isn’t always straightforward, and can cause “angst,” as Udall puts it.

The law currently says Arizona would have to bear the brunt of any reductions in flow, while Las Vegas could see some more modest restrictions. California, on the other hand, “escapes scot free,” said Udall, meaning farmers there would be the last to see any restrictions.

According to a shortage-sharing agreement signed in 2007, if Lake Mead drops below 1075 feet (328 meters), automatic water cuts will kick in for Arizona, Nevada, and Mexico.

(See how water is “embedded” in things we use every day and see how the world’s river basins stack up.)

Agriculture…and Climate Change

Most Colorado River water is used for agriculture. That’s good in the view of Tina Shields, who manages Colorado River resources for the Imperial Irrigation District in southern California, which mostly serves farmers in a region just above where the Colorado flows into Mexico. (See a series on the Colorado River Delta.)

Shields says people from cities are greedily eyeing farmers’ water. “We shouldn’t be jeopardizing our food supply to allow urban growth to occur,” Shields counters.

To some degree it may feel like the same old fights will wage on. But Udall says water stress may eventually force major changes. He said there are warning signs that climate change is already steering the fight to where it’s never been before.

“Climate change has the potential to throw curveballs—to throw extreme events at us the likes of which we’ve never seen and we’re not prepared to deal with,” said Udall.

Related articles

• Feds cut Colorado River releases; CAP shortage risks increase (azstarnet.com)
• Feds begin Colorado River water drought measures (sacbee.com)
• Feds begin Colorado River water drought measures (sfgate.com)
• Warning sign on the Colorado River (sott.net)
• Is the Colorado River tapped out? (summitcountyvoice.com)
• Drought-induced curb on Lake Powell water is first-ever. (bloomberg.com)
• Feds begin Colorado River water drought measures (trib.com)
• Warning Sign on the Colorado River (news.sciencemag.org)
• How Two Reservoirs Have Become Billboards For What Climate Change Is Doing To The American West (thinkprogress.org)
• Unprecedented Cut in Colorado River Flow Ordered, Due to Drought (wunderground.com)