Озеро Пауэлл: Уровень воды, история и перспективы восстановления каньона Глен.

Reservoir in Utah and Arizona, United States

Full:
Current (June 9, 2023): Environmentalists have pushed to drain Lake Powell and restore Glen Canyon to its natural, free flowing state. The all time highest water level was reached on July 14, 1983, during one of the heaviest Colorado River floods in recorded history, in part influenced by a strong El Niño event. The lake rose to 3708.34 feet (1130 m) above sea level, with a water content of It lies primarily in parts of Garfield, Kane, and San Juan counties in southern Utah, with a small portion in Coconino County in northern Arizona. The northern limits of the lake extend at least as far as the Hite Crossing Bridge.

Colorado River flows have been below average since 2000 as a result of the southwestern North American megadrought, leading to lower lake levels. In winter 2005 (before the spring run off) the lake reached its then lowest level since filling, an elevation of 3555.10 feet (1084 m) and by April 22, 2022, Lake Powell was at 3522.24 feet (1074 m) in elevation – just 22.88 of capacity. This marks the lowest water level for Lake Powell since it was filled in 1963. The capacity of Lake Powell has decreased by 7% since 1963 facing an average annual loss of 33,270 acre feet of storage, due to the inflow of sediments from Colorado and San Juan rivers. Peer reviewed studies indicate that storing water in Lake Mead rather than in Lake Powell would yield a savings of 300,000 acre feet of water or more per year, leading to calls by environmentalists to drain Lake Powell and restore Glen Canyon to its natural, free flowing state.

These data are for the Wahweap climate station on Lake Powell just south of the Utah Arizona border (Years 1961 to 2012).

Glen Canyon was carved by differential erosion from the Colorado River over an estimated 5 million years. The Colorado Plateau, through which the canyon cuts, arose some 11 million years ago. Within that plateau lie layers of rock from over 300 million years ago to the relatively recent volcanic activity. Pennsylvanian and Permian formations can be seen in Cataract Canyon and San Juan Canyon. The Moenkopi Formation, which dates from 230 million years ago (Triassic Period), and the Chinle Formation are found at Lees Ferry and the Rincon. Both formations are the result of the ancient inland sea that covered the area. Once the sea drained, windblown sand invaded the area, creating what is known as Wingate Sandstone. The more recent (Jurassic Period) formations include Kayenta Sandstone, which produces the trademark blue black "desert varnish" that streaks down many walls of the canyons. Above this is Navajo Sandstone. Many of the arches, including Rainbow Bridge, lie at this transition point. This period also includes light yellow Entrada Sandstone, and the dark brown, almost purple Carmel Formation. These latter two can be seen on the tops of mesas around Wahweap, and the crown of Castle Rock and Tower Butte. Above these layers lie the sandstone, conglomerate and shale of the Straight Cliffs Formation that underlies the Kaiparowits Plateau and San Rafael Swell to the north of the lake. The confluences of the Escalante, Dirty Devil and San Juan rivers with the Colorado lie within Lake Powell. The slower flow of the San Juan river has produced goosenecks where 5 mile (8 km) of river are contained within 1 mile (2 km) on a straight line.

Zebra and quagga mussels first appeared in the United States in the 1980s. The mussels were initially brought to the United States through the ballast water of ships entering the Great Lakes. These aquatic invaders soon spread to many bodies of water in the Eastern United States and have even made their way to the western United States. In January 2008, Zebra mussels have been detected in several reservoirs along the Colorado River system such as Lakes Mead, Mojave, and Havasu. By the early 2000s Arizona, California, Nebraska, Kansas, Colorado, Nevada and Utah have all confirmed the presence of larval zebra mussels in lakes and reservoirs. Zebra and quagga mussels can be destructive to an ecosystem due to competition for resources with native species. The filtration of zooplankton by the mussels can negatively impact the feeding for some species of fish. Zebra and quagga mussels can attach to hard surfaces and build layers on underwater structures. The mussels are known to clog pipes including those in hydroelectric power systems, thus becoming a costly and time consuming problem for water managers in the West. Control policies have recently been introduced to alleviate the hydroelectric problems as well as ecological problems faced by Western infestation. Beginning in 1999 Lake Powell began to visually monitor for the mussels. In 2001 hot water boat decontamination sites were established at Wahweap, Bullfrog, and Halls Crossing marinas. In January 2007, zebra mussels were detected in Lake Mead and new action plans were announced to prevent the spread of mussels to Lake Powell. In August 2007, preliminary testing was positive for zebra or quagga larvae in Lake Powell. These tests were deemed false positives, but adult quagga mussels were found in 2013. In August 2010, Lake Powell was declared mussel free. Lake Powell introduced a mandatory boat inspection for each watercraft entering the reservoir beginning in June 2009. Effective June 29, 2009, every vessel entering Lake Powell must have a mussel certificate, although boat owners were allowed to self certify. These measures were intended to help prevent vessels from transporting Zebra mussels into Lake Powell. Despite these measures, quagga mussel DNA was detected in 2012 and live mussels were found at a number of sites including the Wahweap Marina in Spring and Summer 2013. In June 2013 the NPS was attempting a diver based eradication program to find and remove mussels before the lake became infested.

The Washington County Water Conservancy District has proposed building the Lake Powell Pipeline, which would have the capacity to extract up to per year from Lake Powell for distribution to municipal drinking water systems in the county.