Seven hydropower dams were built on the Coosa River in Alabama in the mid-1900s, but American Rivers wants the U.S. Fish and Wildlife Service to insist on protections for wildlife in the license for Alabama Power Co. to operate the dams for the next 50 years.
View related photos
updated 4:53 p.m. ET June 2, 2010
PHILADELPHIA - The Upper Delaware River in New York State, the source of drinking water for 17 million people, is the most endangered river in the United States, according to a new report.
It is one of 10 rivers on a list, compiled by U.S. environmental group American Rivers, which are threatened due to causes such as natural gas drilling, mining and poor flood management.
The Upper Delaware topped the list because of the threat of contamination from chemicals used in gas drilling in New York and on the Pennsylvania side of the watershed.
Gas drilling was also the reason why the Monongahela River in western Pennsylvania was rated ninth on the list.
Others endangered rivers include the Gauley River in West Virginia, which came in third and is threatened by mountain-top mining, and the Upper Colorado River, which is sixth and has been diminished by water diversions. The report said it could become "a shadow of its former self" if two new diversion projects proceed.
The Sacramento-San Joaquin River Delta in California was second on the list, and Little River in North Carolina and Cedar River in Iowa rounded out the top five.
The Little River is under threat because of a proposed new dam. But American Rivers said the project could be avoided by improved water-efficiency methods and the expansion of existing reservoirs.
Troubled water: 10 rivers at risk
Rivers across the nation are on an environmental group's annual list of the 10 most endangered U.S. waterways.
In the Upper Delaware campaigners are trying to prevent gas drilling in the Marcellus Shale, a major source of natural gas that lies beneath the river's watershed.
"This clean water source is threatened by natural gas extraction activities in the Marcellus Shale, where chemicals injected into the ground create untreatable toxic waste water," American Rivers said.
The group urged the Delaware River Basin Commission, an interstate regulator, to deny drilling permits to energy companies until it fully investigates whether a drilling technique called "fracking" poses a threat to the river's water.
American Rivers also wants Congress to pass legislation that would give the federal government oversight of the drilling industry, and require companies to meet requirements on disclosure of chemicals.
Other endangered rivers include the Upper Colorado River at No. 6, the Chetco River in southern Oregon, the Teton River in Idaho and the Coosa River in Alabama.