River Basin hasn’t been this dry since the late 16th century
By BRENT ISRAELSEN
The Salt Lake Tribune
The Colorado River and its tributaries begin without drama, dripping from snowfields 14,000 feet above sea level. By the time they reach places like the Gates of Lodore in northwestern Colorado and Cataract Canyon in southern Utah, they are raging torrents, scouring the landscape with earsplitting fury before running into giant manmade dams that put an end to the river's fury!
During the past five years, the river has met an even more formidable foe: a prolonged drought.
This "early 21st century drought," as scientists now call it, is believed to be the most severe in more than a century.
Since 1999, annual water inflows to Lake Powell have averaged 7.1 million acre-feet (MAF) well below the 12.4 million acre-feet average during the previous 100 years and less than half the 15.1 MAF volume that was the basis for dividing the river among seven states in 1922. (One MAF equals about 326 billion gallons.)
This year's inflow is forecast at a dismal 5.6 MAF, according to a new report from the U.S. Geological Survey (USGS).
During the past five years, the river's average annual flow into Lake Powell is smaller than it was during the dustbowl years of the Depression, when the flow averaged about 10.2 MAF.
"We're in a nasty midterm drought," says Tom Ryan, hydrologist for the U.S. Bureau of Reclamation, which manages the dams on the Colorado River, the biggest single source of water in the Southwest.
According to tree-ring data, it hasn't been this dry in the Colorado River Basin since the late 16th century--about the time Shakespeare began writing his plays. At that time, the river was running at an annual average of about 8.8 MAF.
"The current drought may be comparable to or more severe than the largest-known drought in 500 years," states a new USGS report.
What the tree-ring and other historical evidence cannot predict, however, is what will happen in the coming years.
"The question is, where are we moving?" says David Meko, associate research professor at the Laboratory of Tree Ring Research at the University of Arizona.
Meko noted that the last prolonged drought in the river basin, in the late 1970s, was followed by an extremely wet period in the early 1980s that forced flood-control releases from Glen Canyon Dam on Lake Powell, which used to fill nearly every year in the 1980s and '90s. The current drought has pulled Lake Powell down to about 42 percent of capacity. Ryan predicts it will take 15 years of normal precipitation to fill the reservoir again, although a wet cycle like that of the early 1980s could fill it in four years.
Farther downstream, Lake Mead behind Hoover Dam in Nevada is down to 51 percent of capacity.
The surfac e of the lake, which supplies 85 percent of Las Vegas’ water, has dropped to about 1,125 feet, becoming uncomfortably close to the 12-foot-diameter intake for one of the pipelines that sends water to Sin City.
The upper layer of the lake contains lower-quality water that can overtax water-treatment plants.
To reach deeper and cleaner water, the Southern Nevada Water Authority is spending an unanticipated $6.4 million this summer to install a "sleeve" that would extend the intake downward another 70 feet.
"If the lake were higher, we would not have to pursue this project," said Marc Jensen, the Las Vegas water agency's director of engineering.
Despite the less-than-cheery news about low lake levels and river flows, federal officials say they are far from panic mode.
The reservoirs on the Colorado River are doing what they are designed to do, says Ryan. "People became accustomed to seeing Lake Powell full or near full. I don't think people know that Lake Powell was meant to go down."
Bennett Raley, U.S. Interior Secretary Gale Norton's point man on Western water issues, says the drought is a "serious matter" and a "wake-up call" but not a "crisis."
A few more years of this dryness, however, could test like never before the laws and officials that manage the Colorado River, arguably the most over-allocated in the nation.
"You have to be concerned because you don't know whether you're in the sixth year of a six-year drought or the sixth year of a 15-year drought," says Don Ostler, director of the Upper Colorado River Basin Commission.
Seven states, including Utah, divide the Colorado River, which is governed by interstate compacts, international treaties, several court decrees and federal statutes known collectively as the "Law of the River."
The law has worked reasonably well in recent decades, mainly because there was plenty of water to go around. The upper Colorado River Basin states of Utah, Wyoming, Colorado and New Mexico were using much less than their full share of the river. And abundant precipitation was keeping the river and its reservoirs full of water, providing a "surplus" that allowed the lower basin states of Nevada, Arizona and California to use more than their legal share.
The time of plenty on the river appears to be over.
The upper basin states along with American Indian tribes are planning to increase their take of the river at the same time Lake Powell – the "bank account" that helps the upper basin meet its obligations to the lower basin--is shrinking.
'If the drought continues, Powell could reach its lowest outlet, located at 3,370 feet above sea level, in three years. At that point, only water that flows into the reservoir will be allowed to flow out of it, making contractual water deliveries to the lower basin more difficult. Power generation from Glen Canyon's hydroelectric turbines would come to a virtual standstill, as would motorized boat recreation.
"There is the potential for significant problems, particularly for the lower Colorado River Basin," says Ostler. "That basin has become accustomed to using surplus water. In a drought, you don't have surplus water. That can put them in a bind."
Arizona, which holds the most junior rights on the river, would be hit first, followed by Mexico and Nevada. California, with its senior rights, would be the last to be affected by shortages, although the state only recently has been living within its 4.4 MAF share of the river.
Las Vegas would suffer the most from shortages, because, unlike the other river users, it has no agricultural "buffer" in its 300,000 acre-foot share. Cutbacks would be passed on directly to homeowners and businesses, including the giant casinos and resorts upon which the city has built its economy.
Declaring shortages on the river will not be an easy task for the Interior Department, which would find itself caught in a heated feud between jealous states.
"There are some absolutely intriguing questions about the relationship between the upper basin and the lower basin that we'll answer as time goes on," says Raley. "But unlike prior times, when all the fights were almost always about the future, the drought will be about now.
"We only have so much water and no [interior] secretary can increase that."
But Interior, Congress and the Colorado River states should re-examine the river's limits and adjust the Law of the River accordingly, says Owen Lammers, director of Living Rivers, a Moab-based environmental group.
"We should be preparing for significantly lower flows than were planned for 80 years ago."
