{"id":42005,"date":"2022-02-24T17:50:58","date_gmt":"2022-02-25T00:50:58","guid":{"rendered":"https:\/\/dh.durangoherald.com\/tj\/federal-water-projections-for-lake-powell-other-reservoirs-are-too-rosy\/"},"modified":"2022-02-25T00:50:58","modified_gmt":"2022-02-25T00:50:58","slug":"federal-water-projections-for-lake-powell-other-reservoirs-are-too-rosy","status":"publish","type":"post","link":"https:\/\/dh.durangoherald.com\/tj\/federal-water-projections-for-lake-powell-other-reservoirs-are-too-rosy\/","title":{"rendered":"Federal water projections for Lake Powell, other reservoirs are \u2018too rosy\u2019"},"content":{"rendered":"

\"A
A boat cruises along Lake Powell on July 31 near Page, Arizona. This summer, water levels hit a historic low amid a climate change-fueled megadrought engulfing the West. (Rick Bowmer\/The Associated Press)<\/span>Rick Bowmer\/The Associated Press<\/span><\/figcaption><\/figure>\n<\/p>\n

The Bureau of Reclamation\u2019s influential monthly forecasting report for water levels at Lake Powell and other reservoirs are consistently \u201ctoo rosy,\u201d said one of the five experts who co-published a new Colorado River basin research paper.<\/p>\n

Each month, the Bureau of Reclamation, which manages Lake Powell, releases a widely read report known as the 24-Month Study. The document projects three scenarios of monthly conditions in the Colorado River basin two years out \u2014 a most probable outcome as well as a best- and worst-case scenario. The August version of the 24-Month Study is particularly important; the bureau uses that report to determine how it will operate the basin\u2019s reservoirs for the upcoming calendar year. The bureau also uses the April forecast to make decisions about Lake Powell operations.<\/p>\n

\u201cWe\u2019re all living and breathing these 24-month studies and these studies include a range of uncertainty,\u201d said Jack Schmidt, director of the Center for Colorado River Studies at Utah State University, which published the paper. \u201cWe decided to go under the hood on this for no particular reason other than this is an important piece of the puzzle that is guiding a lot of public conversation.\u201d<\/p>\n

The paper, titled \u201cEvaluating the Accuracy of Reclamation\u2019s 24-Month Study Lake Powell Projections,\u201d found that the bureau\u2019s most-probable calculation in the August study \u201ctended to overestimate the end-of-calendar-year Lake Powell elevation by as much as ~10 feet.\u201d Similarly, the study, released Feb. 18, found that the April forecast for end-of-year elevation numbers were off by as much as 20 feet in either direction.<\/p>\n

Ten or 20 feet can make a big difference at Lake Powell these days. Water managers are closely watching whether the water level will drop below 3,525 feet above sea level. If it does, it threatens the ability of Glen Canyon Dam to generate power. More than 3 million customers use Glen Canyon Dam electricity and the federal government generates roughly $150 million in average annual revenue from selling that hydropower. Brad Udall, a senior water and climate research scientist at Colorado State University\u2019s Colorado Water Institute, said the water level at Lake Powell could dip below that point at the end of this year or early next year.<\/p>\n

Last summer, U.S. water engineers made emergency releases from other reservoirs, including Blue Mesa west of Gunnison, to protect the water level at Lake Powell. The releases dropped the water level at Blue Mesa 8 feet, which forced an early end to the boating season and significantly impacted the local economy.<\/p>\n

Bureau of Reclamation public affairs officer Patti Aaron said the bureau appreciates the kind of academic analysis contained in the Colorado River Studies paper and is reviewing the research.<\/p>\n

The short-term projections in the 24-Month Study are based on widely accepted hydrologic models compiled by NOAA\u2019s Colorado Basin River Forecast Center; the more long-term projections, however, are made based on an analysis of average inflows during the 30 years from 1991 through 2020. That\u2019s a problem, according to the new report.<\/p>\n

\u201cReclamation uses the last 30 years of flow data to run these projections. And because the last 30 years includes the end of the 20th century, which was quite wet, it makes these projections think the future is rosier than it is,\u201d Udall, a co-author of the research paper, said.<\/p>\n

Until last year, the Bureau\u2019s 24-Month Study used a 30-year period that included the 1980s. The latest update drops the 1980s and adds in the 2010s, which helps, Udall said. But Udall advocates going further by dropping the 1990s from the projections and just relying on data from the past 20 years. This approach, he said, would provide a more accurate picture.<\/p>\n

Climate scientists who studied tree ring data have recently identified the current 22-year period as the driest on record stretching back 1,200 years. The report, published in the journal Nature Climate Change, estimated that climate impacts driven by human causes increased the severity of the drought by 42%.<\/p>\n

\u201cAs water supplies fundamentally change we\u2019re going to have serious problems if we use these older statistics to consider our risk,\u201d Udall said. \u201cThe climate is not stable and if we utilize this old data, it\u2019s too rosy.\u201d<\/p>\n

In 2000, for example, the reservoir system in the basin was 95% full; as of fall 2021, the reservoirs were at 39% capacity, the lowest levels on record, according to the Department of the Interior.<\/p>\n

\u201cWhat we expect to see based on the most probable scenario doesn\u2019t reflect the changes we\u2019ve seen in the climate,\u201d Eric Kuhn, who was the general manager of the Colorado River District for 37 years, and a co-author on the paper, said.<\/p>\n

Kuhn, now an author who writes about Colorado River issues, said what surprised him most upon reflecting on the paper\u2019s findings is why this topic doesn\u2019t come up more often. \u201cWhy hasn\u2019t the water management community had discussion about this before?\u201d Kuhn said. \u201cI\u2019m hopeful this will help to have more discussion of general management.\u201d<\/p>\n

\u201cWe need to plan for something different.\u201d Udall said. \u201cThat\u2019s why we\u2019re trying to prompt a discussion around this.\u201d<\/p>\n

Read more at The Colorado Sun<\/div>\n

The Colorado Sun is a reader-supported, nonpartisan news organization dedicated to covering Colorado issues. To learn more, go to coloradosun.com<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"

Colorado River researchers find Bureau of Reclamation study was consistently too optimistic<\/p>\n","protected":false},"author":1,"featured_media":42006,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[],"tags":[233,1030,28,295,294],"naviga_topic":[],"class_list":["post-42005","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","tag-coloradosun-com","tag-environment","tag-headlines","tag-water","tag-water-supply"],"acf":[],"author_name":"dh_admin","_links":{"self":[{"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/posts\/42005","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/comments?post=42005"}],"version-history":[{"count":0,"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/posts\/42005\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/media\/42006"}],"wp:attachment":[{"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/media?parent=42005"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/categories?post=42005"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/tags?post=42005"},{"taxonomy":"naviga_topic","embeddable":true,"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/naviga_topic?post=42005"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}