Editor's Note: Expedition Blue Planet, led by Jacques Cousteau's granddaughter Alexandra Cousteau, is traveling 14,500 miles of road over 138 days to investigate and film some of North America's most pressing water-use and management stories. Each week expedition members will file a dispatch from the field for Scientific American until the expedition concludes on November 12 in Washington, D.C. This is their first blog post.

Coordinates: 35.21°N 80.84°W, Watershed: Catawba River

On Monday, Avner Vengosh, an environmental and aqueous geochemist at Duke University in Durham, N.C., gathered samples from Mountain Island Lake to study how the two coal-ash ponds that discharge into it are affecting its water and lake sediment. The discharge for the coal-ash ponds lies just around the corner and upstream from the intake for 80 percent of Charlotte, N.C.'s drinking water.

It was timely science. On Tuesday, the EPA hosted a public hearing in Charlotte, one of eight such city hearings, to decide whether coal ash should be classified as hazardous waste.

"Absurd doesn't even do justice to the ridiculousness of what the coal industry's allowed to do to our drinking water," Dave Merryman, Catawba Riverkeeper from Charlotte, tells me at a water-themed street fair  that Expedition Blue Planet co-hosted at Central Piedmont Community College, in Charlotte, N.C., last week. He and other locals are fighting to prevent another Kingston coal-ash spill from happening on their turf. At the water street fair, he's busy recruiting people to testify at the hearing to bolster the case against coal ash.

The Tennessee Valley's Kingston spill released over 4.1 million cubic meters of coal-ash slurry, laden with heavy metals, into the surrounding waterways in 2008. To give you an idea of just how large it was, back of the envelope calculations suggest the volume of coal ash spilled was roughly eight times larger than the oil reported to gush out of Deepwater Horizon.

"What you basically have in a coal ash pond is a slurry of toxic compounds," says Bill Gupton, chair of the Central Piedmont Sierra Club, from his booth at the water village. "If we have a flood like the Tennessee Valley [here] then three quarters of a million people will be at risk because it will ruin our water supply."

Talking with Merryman and others at the water village was a great opportunity for us. Not only is it a pressing issue for them, but Expedition Blue Planet will be visiting Tennessee to film a documentary on the Kingston spill later this month.

Last April, Merryman tested the water at Mountain Island Lake and found arsenic levels two and a half times higher than the state standard.

But Vengosh's ongoing work in the Tennessee Valley since the 2008 coal-ash spill suggests that may be the tip of the iceberg. He found that water within the river sediment downstream from the Kingston spill has extremely high levels of arsenic, which can bio-accumulate in the ecosystem. The river sediment's "pore water" clocked 2,000 parts per billion (ppb) of arsenic. Drinking water's threshold is 10 ppb and that of the ecological system is 150 ppb.

"We're finding that if you allow ash to interact with water, you end up generating effluent that is high in different contaminants which are bad for either human health or the ecological system," Vengosh explained in a telephone call. 

At the end of the day, the smokestack scrubbers in "clean coal" plants clean the air but at a cost, he said: "They stop the emission of pollutants to the atmosphere but it's moving into the coal ash and you're moving it from the air to the water."

Image credit: © Catawba Riverkeeper Foundation