From inkstain (John Fleck):
The Bureau of Reclamation is going to tell us Friday that there’s not very much water in Lake Powell, and that as a result releases from Powell will be curtailed in the coming year, which sets off a cascading set of effects downstream. I took a crack at explaining this here, but Brett Walton has really done the journalistic heavy lifting to explain what it all means. I don’t have much to add to Brett’s analysis, which is rich and detailed, except for this simple takeaway message: You’ll hear from and see a lot of people in coming days running around like their hair is on fire about this. Chill. As Brett’s piece explains, this is an orderly process.
Here’s the post that Mr. Fleck cites above from Circle of Blue (Brett Walton). Click through and read the whole thing. Here’s an excerpt:
Every month, officials at the federal Bureau of Reclamation, the dam-master for the river, run some hydrological assumptions and observations through a computer, peer into the crystal screen, and see a rough outline of the system’s health for the following two years. The 24-month study, as it is called, has taken on greater significance since 2007, when the seven U.S. states that share the Colorado River signed an agreement that declared the study as the guidepost for how to operate the Basin’s two big reservoirs, Mead and Powell, in times of water surplus and water deficit. (The 2007 shortage-sharing agreement, known formally as the Colorado River Interim Guidelines for Lower Basin Shortages, did not include Mexico, which is guaranteed water from the river under a 1944 treaty. Mexico’s obligations during a shortage were worked out in an amendment called Minute 319, signed last November.)
Every year since the shortage-sharing agreement was signed, the August study — the 2013 version of which will be released this Friday — has been the standard-setter. Its projections determine how much water the Bureau will send downstream in the next year. If the results from last month hold, as is likely, the amount of water released from Lake Powell in 2014 will be the lowest since the reservoir was being filled during the 1960s. The resulting 9 percent cut would set the table for the first-ever shortage declaration on the Lower Colorado River, either in 2015 or 2016. By then, the water level in Lake Mead, downstream from Powell, is projected to drop below a trigger point that sets off a round of restrictions on water withdrawals for Arizona, California, Nevada, and now Mexico…
Yet, if Lake Mead were to fall below 327.7 meters (1,075 feet) in elevation, thus breaching the first of three shortage levels named in the 24-month study, the short-term effects would not be devastating: there would be a belt-tightening by a small group of users in Arizona and Nevada, a price increase for a larger group in Arizona, and a firm cap on withdrawals in California. In practice, water use would likely remain constant, because groundwater pumping — itself an unsustainable safety net — would rise to offset the restriction on surface diversions…
The first number to watch for is 1,089.7 meters (3,575 feet). If Friday’s study projects that Lake Powell’s elevation will fall below the 3,575-feet barrier in January of 2014 — as the July study showed — then a shortage for the Lower Basin is all the more likely by 2016, because of the smaller slug of water that the Bureau would release from Powell. Shortages, however, are declared based on Lake Mead’s elevation and would affect only Arizona, California, and Nevada.
Bruce Williams, who works for the Bureau’s river operations group, says that dry soils and below-average rainfall for 2013 point to a similar forecast for this month’s study as was predicted last month.
“Based on everything going on in the Basin, the odds are that July is close to what we’ll see in August,” Williams told Circle of Blue.
If that happens, then attention turns to Lake Mead. The 2007 shortage-sharing agreement sets three reservoir elevations under which water restrictions are imposed on the Lower Basin: 1,075 feet, 1,050 feet, and 1,025 feet. Under the first shortage level, total water use is cut by 4.4 percent in the three Lower Basin states: Arizona would take an 11 percent cut and Nevada 4 percent, while California’s allocation would not be reduced. Mexico’s deliveries would be take a 3.3 percent hit.
From The Imperial Valley Press (Antoine Abou-Diwan):
Under standard conditions, the BOR releases 8.23 million acre-feet of water from Lake Powell to Lake Mead to keep the two reservoirs operating in harmony. However, this year’s annual release volume could be less than standard. Fourteen consecutive years of drought, reduced inflows to the Colorado River and urban population growth have squeezed water supplies. Diversions from the Colorado River deliver water to California, six other western states and parts of Mexico. “If on Friday the 24-month study puts us in operational mid-release tier, it could mean that this year’s annual release volume could be less than standard. It would be 7.48 million acre-feet,” said Lisa Iams, Upper Colorado Region public affairs officer.
Lake Powell and Lake Mead are BOR’s two storage reservoirs on the Colorado River. The BOR tries to maintain a balance in the water level between the two reservoirs, and reduced inflows to Lake Powell generally mean lower releases to Lake Mead, which lies downstream of Lake Powell. While a lower release does not necessarily correspond with a declaration of a water shortage, the likelihood of such an occurrence will increase if conditions on the river remain the same.
The water level on Lake Mead will drop four to eight feet more than it would under standard releases, bringing the lake within 31 feet of its shortage trigger, said Tina Shields, Imperial Irrigation District assistant water manager. “It’s not a shortage until Lake Mead reaches an elevation of 1,075 (feet),” Shields said.
A shortage declaration on the lower Colorado River Basin would not directly impact California, Shields said. Arizona, Nevada and Mexico would be first to feel the pinch. However, California’s inadvertent overrun policy would be suspended, putting a hard cap on California’s allocation. Under the Colorado River Compact, California has an entitlement of 4.4 million acre-feet of water per year.
From the Oakland Press (Brian Maffly):
July’s actual flow into the reservoir separating the Colorado River’s upper and lower basin turned out be about 100,000 acre feet less than forecast, or 13 percent of July’s normal inflows, according to Michelle Stokes of the National Oceanic and Atmospheric Administration. “That was the huge shocker. The month before was 35 percent of normal,” said Stokes, the hydrologist in charge of NOAA’s Colorado Basin River Forecast Center. And the outlook for the next several months is not much better.
It is widely expected that this new data will prompt the U.S. Bureau of Reclamation to reduce Glen Canyon releases next year by 750,000 acre feet, enough water to supply 1.5 million homes. “We had very low years the past two years, almost record lows for the upper basin,” Stokes said. “We are starting with relatively dry soils and low flows. Our forecast is for below normal, 80 percent. We are thinking 33 percent in August and 44 percent in September, 60 to 70 in October.”
From Colorado River Setting the Course:
Water policy experts convening at the annual Clyde Martz Summer Water Conference in Boulder, Colo. (Aug. 15-16), are abuzz about an unprecedented alarm in the Colorado River Basin. Amidst the driest 14 years on record in the Southwest, for the first time in history the Bureau of Reclamation (BOR) will likely reduce the amount of water that Lake Powell releases to Lake Mead – an alarm that could be the first indication of serious water shortages ahead.
Western Resource Advocates (WRA) and Environmental Defense Fund (EDF) have prepared a fact sheet to help explain the significance of the Lake Powell release reduction. [Download the Fact Sheet here (PDF)]
“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.”
More Colorado River Basin coverage here.