The Colorado was among ten rivers that the environmental group American Rivers identified as facing imminent threats,in a list released on Tuesday.The rivers on the list aren’t necessarily the most imperiled or polluted,says Sinjin Eberle,the group’s associate director of communications for the Colorado River Basin.To book the Grand Canyon West Rim bus tours from Las Vegas on the website with discount price.

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The stretch of the Colorado River that winds through the Grand Canyon tops a new list of the nation’s most endangered rivers,a reflection of controversial plans to reopen a uranium mine in the area and build a tramway that would take visitors to a new restaurant and river walkways on the canyon floor.Rather,they are the ones that the advocacy group is urging the public to ask government agencies to protect in the coming months.

Other rivers on the list include the Columbia River in Washington and Oregon,where the group says that outdated dams have decimated populations of salmon and steelhead;the Holston River in Tennessee,which is under threat from chemical pollution;the Smith River in Montana,where the group says a proposed copper mine threatens the river’s wild trout population;and the St.Louis River in Minnesota,where the group says a proposed copper-nickel sulfide mine threatens drinking water and wildlife.

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During the past several million years,the Colorado has sliced through layers of limestone,sandstone,and shale,creating a canyon in Arizona that is more than a mile deep in places.And although it’s still awe-inspiring and occasionally unpredictable,the river has been transformed by dams upstream that have altered its flows and water temperatures,as well as by pollution and nearby development.

The 277-mile stretch of the lower Colorado is ranked first on the group’s list because of three proposals:the planned reopening of a nearby uranium mine,the proposed 1.6-mile tramway that would help tourists get from new commercial developments on the canyon’s rim to the canyon’s floor,and a major expansion of the Arizona town of Tusayan.

A mining company,Energy Fuels Resources,is seeking to reopen the Canyon Mine near the south rim of the Grand Canyon and sink an additional 1,200 feet of shaft to reach ore.

In 2012 the Obama administration announced a federal moratorium on new mining claims in the area,but four existing mines remain near the canyon.

“They’re casually called‘zombie mines,’because when the price of uranium goes down,the mines pause their operations and start operating again when the price rises,”Eberle says.“That’s happening right now.”

Uranium has contaminated groundwater in the area.Because of radioactive runoff on the South Rim,the National Park Service warns hikers not to drink the water in a nearby creek.

But Energy Fuels Resources spokesperson Curtis Moore said that naturally occurring uranium deposits eroding into the canyon have more impact on the park than do the mines outside its boundaries.