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Lake Powell

2007 Schools Wikipedia Selection. Related subjects: General Geography

                               Lake Powell above Warm Creek Bay

                               Lake Powell above Warm Creek Bay
                                                                    Facts
                                   Start of storage         March 13, 1963
                      Completion of initial filling          June 22, 1980
                                          Elevation       1,127 (3,700 ft)
                                   Volume (maximum)            33.304 km³
                                                    (26,999,814 acre.feet)
                                   Volume (current)            ~ 26.5 km³
                                                    (21,483,757 acre.feet)
                                       Surface area                266 mi²
                                             Length     299 km (186 miles)
                                              Width       40 km (25 miles)
                                          Shoreline 3,057 km (1,900 miles)
                                      Maximum depth         170 m (560 ft)
                                         Mean depth          40 m (132 ft)

   Lake Powell is a man-made reservoir on the Colorado River, straddling
   the border between Utah and Arizona. It was created by the flooding of
   Glen Canyon by the controversial Glen Canyon Dam, which also led to the
   creation of Glen Canyon National Recreation Area, a popular summer
   destination. The reservoir is named for explorer John Wesley Powell, a
   one-armed American Civil War veteran who explored the river via three
   wooden boats in 1869. In 1972, Glen Canyon National Recreation Area was
   established. It is public land managed by the National Park Service,
   and available to the public for recreational purposes. Lake Powell is
   arguably one of the most scenic lakes in America, situated in some of
   Southern Utah's finest red-rock desert country. It is second in size
   only to Lake Mead downstream. With both lakes storing about 25,000,000
   acre-feet (31 km³) of water each when full, the water is a valuable
   resource for the western U.S. Lake Powell boasts over 1,900 miles (3100
   km) of shoreline, more than the entire coast of the western U.S. and
   has 96 major side canyons.

History

   In the 1940s and early 1950s, the U.S. Bureau of Reclamation planned to
   construct a series of Colorado River dams in the rugged Colorado
   Plateau province of Colorado, Utah and Arizona. Glen Canyon Dam was
   born of a controversial damsite the Bureau selected in Echo Park, in
   what is now Dinosaur National Monument in Colorado. A small but
   politically effective group of objectors led by David Brower of the
   Sierra Club succeeded in defeating the Bureau's bid, citing Echo Park's
   natural and scenic qualities as too valuable to submerge.

   But by agreeing to a relocated damsite near Lee's Ferry, between Glen
   and Grand Canyons, Brower did not realize what he had gambled away. At
   the time, Brower had not actually been to Glen Canyon. When he later
   saw Glen Canyon on a river trip, Brower was stunned to discover that it
   had the kind of scenic, cultural and wilderness qualities often
   associated with America's finest national parks. Over 80 side canyons
   in the colorful Navajo Sandstone contained clear streams, abundant
   wildlife, arches, natural bridges, and thousands of Native American
   archeological sites. By then, however, it was too late to stop the
   Bureau and its commissioner Floyd Dominy from building Glen Canyon Dam.
   Dominy was a firm believer in subduing the river for human use, once
   saying "Now I admit that nature can't improve upon man. We're probably
   the supreme being." Brower believed the river should remain free, and
   would forever after consider the loss of Glen Canyon his life's
   ultimate disappointment.

   Construction on Glen Canyon Dam began with a demolition blast keyed by
   the push of a button by President Dwight D. Eisenhower at his desk in
   the Oval Office on October 1st, 1956. The first blast started clearing
   tunnels for water diversion. On February 11th, 1959, water was diverted
   through the tunnels so dam construction could begin. Later that year,
   the bridge was completed, allowing trucks to deliver equipment and
   materials for the dam, and also for the new town of Page, Arizona.

   Concrete placement started around the clock on June 17th, 1960. The
   last bucket of concrete was poured on September 13th, 1963. Over 5
   million cubic yards (4,000,000 m³) of concrete make up Glen Canyon Dam.
   The Dam is 710 feet (216 m) high, with the surface elevation of the
   water at full pool being approximately 3700 feet (1100 m). Construction
   of the Dam cost $155 million, and 18 lives were lost in the process.
   From 1963 to 1966, turbines and generators were installed for
   hydroelectricity. On September 22nd, 1966, Glen Canyon Dam was
   dedicated by Lady Bird Johnson.
   This is the southwestern portion of Lake Powell, which lies in Arizona.
   The back of Glen Canyon dam can be seen to the right in this image.
   Enlarge
   This is the southwestern portion of Lake Powell, which lies in Arizona.
   The back of Glen Canyon dam can be seen to the right in this image.

   Upon completion of Glen Canyon Dam on September 13th, 1963, the
   Colorado River began to back up, no longer being diverted through the
   tunnels. Lake Powell was born. As the lake filled over the years,
   seismic activity in the area increased as the ground shifted beneath
   the increasing weight of the water. It took 17 years for the lake to
   rise to the high water mark, on June 22nd, 1980. However, in the heavy
   snow year of 1983, the lake crested two meters above the high water
   mark, just two meters below the top of Glen Canyon Dam. In 1964, Glen
   Canyon Dam was voted Outstanding Engineering Achievement of the year by
   the American Society of Civil Engineers.

   The dam has not lacked for detractors throughout its brief history,
   however. A segment of the American public objected to the dam's
   construction and subsequent submerging of Glen Canyon. Many consider
   the dam a symbol of the price of growth in the West. In the past
   decade, this controversy has been steadily making news as people
   continue to contest the dam and push for its decomissioning.

   In April 2005, several years of drought reduced Lake Powell to a low 34
   percent of capacity. In 2004, Glen Canyon National Recreation Area was
   forced to close four of its six boat launching facilities, as the
   receding water left them high and dry. As a sign of the hazards of a
   low reservoir, some of the closed facilities remained partially
   available on a "launch at your own risk" basis. Houseboats not
   frequently moved were stranded by the falling water level. In 2005, the
   runoff returned to normal. The reservoir rose by 55 feet (17 m), and
   all the facilities and ramps were reopened. However, 2006 was another
   dry year, with only about 73% of average runoff. The lake has dropped
   again, and all but one of the boat ramps are unusable for most boats. A
   flurry of articles appeared during these years that drew public
   attention to the chance to see Glen Canyon reemerge from the waters.
   Many features of Glen Canyon not seen in 40 years were once again
   available for all to see. It remains questionable whether or not there
   will be enough water to sustain the lake in years to come.

Geology

   Lake Powell from space
   Enlarge
   Lake Powell from space

   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 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, the result of more compressed sand dunes.
   Many of the arches, including Rainbow Bridge, lie at this transition
   point. This period also includes light yellow Entrada Formations, 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 Straight Cliffs Sandstone
   and conglomerate shales that make up the Kaiparowits Plateau and San
   Rafael Swell to the north of the lake.

   The confluences of the Escalante River and San Juan River lie within
   Lake Powell. The slower flow of the San Juan has produced incredible
   Goose Necks, where 5 miles of river are contained within 1 mile on a
   straight line.

Features

   Rainbow Bridge
   Enlarge
   Rainbow Bridge

   The lake's main body stretches up Glen Canyon, but has also filled many
   (over 90) side canyons. The lake also stretches up the Escalante River
   and San Juan River where they merge into the main Colorado River. This
   provides access to many natural geographic points of interest as well
   as some remnants of the Anasazi culture.
     * Rainbow Bridge National Monument
     * Defiance House ruin
     * Cathedral in the Desert ( photos)
     * San Juan goosenecks
     * Kaiparowits Plateau
     * Hole-in-the-Rock crossing
     * the Rincon
     * Three-Roof Ruin
     * Padre Bay

Development

   Because most of the lake is surrounded by steep sandstone walls, access
   to the lake is limited to developed marinas:
    1. Lees Ferry Subdistrict
    2. Page/ Wahweap Marina
    3. Antelope Point Marina
    4. Halls Crossing Marina
    5. Bullfrog Marina
    6. Hite Marina

   The following marinas are accessible only by boat:
    1. Dangling Rope Marina
    2. Rainbow Bridge National Monument
    3. Escalante Subdistrict

   Glen Canyon National Recreation Area draws more than two million
   visitors annually. Recreational activities include boating, fishing,
   waterskiing, jet-skiing, and hiking. Prepared campgrounds can be found
   at each marina, but many visitors choose to rent a houseboat or bring
   their own camping equipment, find a secluded spot somewhere in the
   canyons, and make their own camp (there are no restrictions on where
   visitors can stay). Anyone who camps further than a quarter of a mile
   from a marina, however, must bring a porta-potty. The burying of human
   waste in Glen Canyon National Recreation Area is prohibited. Pet waste
   must also be packed out.

   The southwestern end of Lake Powell can be accessed via U.S. Highway 89
   and Arizona State Route 98. Use Utah SR-95 and Utah SR-276 to get to
   the northeastern end of the lake.

   Retrieved from " http://en.wikipedia.org/wiki/Lake_Powell"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
   Documentation License. See also our Disclaimer.
