The Potomac River snakes through Washington, D.C., on its way to the Chesapeake Bay, drawing visitors and wildlife to its scenic shores. But the watershed of the nation's capital is currently the most endangered in the United States, according to this year’s list by American Rivers, a conservation group that has been ranking troubled rivers since 1986.

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Even though the Potomac is much cleaner than it used to be, pollution remains a problem, according to the organization. The Nation’s River is threatened by many of the same problems plaguing other waterways across the country, including natural gas drilling, new dam construction and cutbacks in Congress for clean water legislation.

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With the annual list, American Rivers hopes to bring attention to efforts to protect and restore the country’s clean water resources.

Here is this year’s full list, including each river’s major threats:

1. Potomac River (Maryland, Virginia, Pennsylvania, West Virginia, Washington, D.C.) Threat: Pollution; Clean Water Act rollbacks

2. Green River (Wyoming, Utah, Colorado) Threat: Water withdrawals

3. Chattahoochee River (Georgia) Threat: New dams and reservoirs

4. Missouri River (Colorado, Iowa, Kansas, Minnesota, Missouri, Montana, Nebraska, North Dakota, South Dakota, Wyoming) Threat: Outdated flood management

5. Hoback River (Wyoming) Threat: Natural gas development

6. Grand River (Ohio) Threat: Natural gas development

7. South Fork Skykomish River (Washington) Threat: New dam

8. Crystal River (Colorado) Threat: Dams and water diversions

9. Coal River (West Virginia) Threat: Mountaintop removal coal mining

10. Kansas River (Kansas) Threat: Sand and gravel dredging

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Photo: Potomac River. Credit: Corbis.