The Upper Delaware River, which supplies drinking water to 17 million people in New York, New Jersey, and Pennsylvania, is teetering on being poisoned from shale fracking for natural gas, according to America's Most Endangered Rivers: 2010 edition, released in June by conservation organization American Rivers.

Meanwhile, Congress is considering the Fracturing Responsibility and Awareness of Chemicals Act of 2009, which repeals the exemption for hydraulic fracturing in the Safe Drinking Water Act.

Upper Delaware River's watershed is located on a geological formation known as the Marcellus Shale, which is rich in natural gas reserves that have been tapped by multinational energy corporations. More than 15,000 gas wells are expected to be developed in the next 20 years.

Those companies have requested permits to mix clean water from the river with more than 250 chemicals to make hydraulic fracturing fluid for injection into wells to release the gas. Each well requires 3 million to 5 million gallons of water for fracturing.