Scientists see silver lining in Fed’s latest effort to prevent ‘dead pool’ at Lake Powell

0

A white strip of newly exposed rocks is shown along the walls of the Lake Powell canyon at Antelope Point Marina on Friday, July 30, 2021, near Page, Arizona. It highlights the difference between the current level of the lake and the high water mark of the lake. This summer, water levels hit an all-time low amid a climate change-fueled mega-drought that engulfs the western United States. (AP Photo / Rick Bowmer)

The United States Bureau of Reclamation announced Friday that it plans to adjust Colorado River management protocols in early 2022 to reduce monthly discharges from Lake Powell in a bid to prevent the reservoir from falling further in below historic lows of 2021.

As of Thursday, the nation’s second largest reservoir – part of a Colorado River system that provides drinking water to about 40 million people in the West – stood at an elevation of 3,536 feet. It is 27% of tank capacity, 164 feet below full and just 11 feet above the office’s target altitude of 3,525 feet, designed to give a 35-foot buffer zone before “the dead pool.” Below 3,490 feet above sea level, Lake Powell plunges into an area where the production of hydroelectricity from the water flowing through the Glen Canyon Dam becomes unreliable.

According to a press release from the office, the amended delivery schedule will not change the total amount of water left through the Glen Canyon Dam during the year, but will retain a cumulative total of 350,000 acre-feet between January and April to help Lake Powell recover from depressions that left many of the boat launching ramps unusable at the popular recreation site last summer.

Despite a wet October giving water managers hope the region could progress towards recovery amid a 22-year drought, November was the second driest on record and the Intakes reached 1.5 million acre-feet below the Bureau projections of the previous month. When adjusted December projections predicted Lake Powell to drop below 3,525 feet as early as last February, the agency called in partners from basin states, tribes, federal agencies, non-governmental organizations and managers of the water to design a new management program.

“The adjusted releases are designed to help protect critical elevations on Lake Powell until spring runoff materializes,” the press release said.

A graphic shared by the United States Bureau of Reclamation on January 7, 2022 describes its new plan to reduce scheduled water discharges from Lake Powell in an effort to prevent the reservoir from falling below target levels.

A graphic shared by the United States Bureau of Reclamation on January 7, 2022 describes its new plan to reduce scheduled water discharges from Lake Powell in an effort to prevent the reservoir from falling below target levels.

Scientists, however, are not sure the spring runoff will materialize. In the 22nd year of regional drought, the term “aridification” is gaining ground as the best way to describe what could be a long-term drying out of the American West, influenced by climate change.

“We need to be extra vigilant and cautious because we don’t know what lies ahead,” said Jack Schmidt, director of Utah State University. Colorado River Studies Center in response to Friday’s announcement. “Looking ahead, none of us can know exactly what will happen this year. We had times where we looked great at the end of February, then we had an unusually dry March and the snowpack evaporated. “

Schmidt was the principal author of a white paper published by a group of hydrologists last February which analyzed the future of Colorado River flows under various climate change and use scenarios. Their results predicted that, given drying trends and western population growth, projected basin-wide water consumption rates could cause Lake Mead or Lake Powell to dry up as early as 2050. , the cessation of hydroelectric operations and a negative impact on the Grand Canyon ecosystem.

The water tap: Climate change and climate denial on the Colorado River

“The big point to remember is that under conditions of future drought or gradually decreasing runoff associated with global warming, the reservoir system, the system is not sustainable,” Schmidt explained at the time.

Figure ES-4 from the Center for Colorado River Studies' summary White Paper 6 (2021) shows how the combined water storage in Lakes Powell and Mead would decline under management paradigms that imposed various cuts (colored bands) from following the current trajectory (red line).

Figure ES-4 from the Center for Colorado River Studies White Paper 6 (2021) summary shows how the combined water storage in Lakes Powell and Mead would decrease under management paradigms that imposed various cuts (colored bands) from following the current path (red line).

Wayne Pullan, regional director of the Colorado Upper Basin office, agreed on Friday that there was uncertainty in the system.

“Although the basin experienced significant snowstorms in December, we don’t know what to expect and must do all we can to protect the elevation of Lake Powell,” Pullan said in the press release.

In response to this, the agency plans to continue monitoring the hydrology of the basin and may make further adjustments to protect the elevation of Lake Powell. These could include sending additional water downstream to the reservoir from the Colorado River storage project units in the Flaming Gorge, Blue Mesa and Navajo reservoirs. Bureau officials will also continue to work with upper basin states on a drought response plan, to be released in April 2022.

A deeper look: The water tap: remembering a year of water, or its absence

Schmidt, meanwhile, sees three shades of a silver lining in the Bureau’s apocalyptic Friday announcement.

First, his team concluded in February that the estimates of future consumption calculated by the Upper Colorado River Commission may be overstated, giving the seven states that depend on that supply more leeway. If Western states learn to live better with their water resources, their populations can grow without a reservoir from the Colorado River system, they argue.

The second point, to this end and also outlined in the February report white paperis that opportunities to further expand supply by improving water conservation efforts still abound. It’s an argument often made by environmental groups critical of the per capita water use rates in Washington County, Utah which, by many measures, far exceed those of other similar desert communities.

As Washington County officials call for a $ 2 billion, 140 mile pipeline project to transport water from Lake Powell to St. George, campaigners argue region must consider conservation measures first such as removing sod and increasing water tariffs. The cuts to Colorado River distributions for lower basin states in 2022 that were announced by the Bureau in August have led some to speculate that “St. George will not get their pipeline.” This latest announcement highlighting the limits of Lake Powell could further strain the prospects for this project and ultimately push southwest Utah toward conservation.

“St. George will not have its pipeline”: Some look to Utah amid cuts in the Colorado River

Schmidt’s third positive note in reaction to Friday’s Bureau announcement is that the modified release schedule for Lake Powell better reflects the natural flows of the Colorado River. Environmentalists often criticize the impact of dams on riparian environments. If we are faced with a situation of reduced overall flow, Schmidt says, it makes sense that man-made discharges are particularly reduced during the winter months, when the river is at its lowest in its natural state.

“January is traditionally a high volume month used to generate hydropower. This is, to be honest with you, an unusually high release. So holding water in January, February and March is just making the river a little more natural because nature had low flows during those months, ”Schmidt said.“ So I don’t have a problem with that. . It makes perfect sense from a natural resource point of view and it is even good for the environment. “

Joan Meiners is the environmental reporter for The Spectrum & Daily News as part of The Ground Truth Project’s Report for America initiative. Support his work by make a donation to these nonprofit programs today. To follow Jeanne on Twitter at @beecycles or email him at jmeiners@thespectrum.com.

This article originally appeared on St. George Spectrum & Daily News: Federal government to slow discharge from Lake Powell to Glen Canyon Dam amid drought



Source link

Share.

Comments are closed.