City workers transport a load of sandbags to be used in re-enforcing a levee gate past the Yazoo & Mississippi Valley Railroad Station May 11, 2011 in Vicksburg, Mississippi. The Mississippi river at Vicksburg is expected to crest at a record 58.5 feet. Heavy rains have left the ground saturated, rivers swollen, and have caused widespread flooding in Missouri, Illinois, Kentucky, Tennessee, and Arkansas. (Photo by Scott Olson/Getty Images)

Giant Olympic rings are towed on The River Thames past The Tower of London on February 28, 2012 in London, England. (Photo by Peter Macdiarmid/Getty Images)

A girl holds onto a pole as as she stands in floodwaters flowing from the swollen Bagmati River caused by heavy rainfall in Kathmandu, Nepal August 17, 2015. (Photo by Navesh Chitrakar/Reuters)

Three Boeing 737 fuselages lie on an embankment on the Clark Fork River after a BNSF Railway Co train derailed Thursday near Rivulet, Montana in this picture taken July 4, 2014. A train derailment in Montana this week damaged a shipment of jetliner fuselages and other large parts on its way to Boeing Co factories in Washington state from Spirit Aerosystems, Boeing said on Saturday. (Photo by Kyle Massick/Reuters)

An Orthodox Christian child is baptized during Epiphany celebrations in the Jordan River January 19, 2012 at the Qasir al-Yahud baptismal site near Jericho, in the West Bank. Thousands of pilgrims gathered for the annual celebration at the site that the Eastern churches believes Jesus was baptised by John. (Photo by Uriel Sinai/Getty Images)

Water gushes out from the Xiaolangdi Reservoir on the Yellow River during a sand-washing operation on June 20, 2012 in Luoyang, China. The sand-washing operation, which started on June 19 and will last for about 20 days, is conducted to clear out the silt deposits at the dam. (Photo by China Foto Press)

In this photo taken Wednesday, April 30, 2014, a dragonfly sits on the nose of a Gharial, rare crocodile-like creatures, in the River Chambal near Bhopepura village in the northern Indian state of Uttar Pradesh. The narrow 250-mile stretch of the Chambal is a place of crocodiles and jackals, of river dolphins and the occasional wolf. Hundreds of species of birds, storks, geese, babblers, larks, falcons and so many more, nest along the river. Endangered birds lay small speckled eggs in tiny pits they dig in the sandbars. Gharials, rare crocodile-like creatures that look like they swaggered out of the Mesozoic Era, are commonplace here and nowhere else. (Photo by Altaf Qadri/AP Photo)

The Mike O'Callaghan–Pat Tillman Memorial Bridge is an arch bridge in the United States that spans the Colorado River between the states of Arizona and Nevada. The bridge is located within the Lake Mead National Recreation Area approximately 30 miles (48 km) southeast of Las Vegas, Nevada, and carries U.S. Route 93 over the Colorado River.