Study helps farmers along Dan River make decisions following coal ash spill

Strader, then an area agricultural agent with North Carolina Cooperative Extension, had received calls from downstream farmers in Caswell and Rockingham counties wondering about the impact of potentially toxic trace elements such as arsenic and mercury would have on their operations.

The farmers wondered, Would the coal ash make it unsafe to irrigate their crops from river water? Was water from the river safe for cattle to drink? And would they be able to continue farming if the river flooded its banks and deposited ash on crop and forage land?

“You could tell the farmers were concerned about the long-term viability of the land, and their concerns were legitimate. They needed answers quickly,” Strader recalled. The spill occurred in February, a time when many farmers are planning what to plant for the summer growing season.

“One of their biggest questions to me was, ‘Can we use the river water to irrigate?’ They said, ‘If we can use the water, we are going to plant corn,’” Strader said, “‘but if we can’t use the water to irrigate, we are going to go with soybeans and another crop.’”

For answers, Strader reached out to NC State University’s Department of Soil Science, where faculty experts were just wrapping up a three-year study of how metals are bound in coal ash and how fast they dissolve out. That study was funded by the Tennessee Valley Authority, following the largest U.S. coal ash spill ever, an accident that occurred at the TVA’s fossil plant in Kingston in 2008.

Dr. Dean Hesterberg, William Neal Reynolds professor of soil science, used the knowledge and experience he’d gained while working on the TVA study to guide the intensive Eden study with Dr. Matt Polizzotto, assistant professor, and Dr. Carl Crozier, professor and Extension specialist.

Using water-quality trend data from both the U.S. Environmental Protection Agency and Duke Energy – data that proved to be consistent – the scientists issued a report in mid-April that delivered good news: The river water was suitable for irrigating crops and as drinking water for livestock.

The report’s findings were conveyed to area farmers and key federal and state agencies, and they garnered widespread coverage by local, state and national news media outlets.

Cautioning that flooding or drought could change the conditions measurably, the researchers included in their assessment practical considerations for farmers who planned to irrigate with Dan River water: Farmers should monitor water-quality information sources, such as those hosted by the EPA, they said. They should avoid irrigating when total metal concentrations or total suspended solids – the solid particles floating in water, including ash particles and soil particles eroded into the river – are elevated above water-quality standards. They should ensure that irrigated water comes from near the river’s surface rather than from its bottom. And they should test area agricultural soils and crop tissues annually.

Now, a follow-up study that Hesterberg and soil science colleagues have embarked on will help farmers, by providing additional assurances about the health of the soils on which their livestock and crops depend. Soil Science and Crop Science colleagues collaborating on the project include Drs. Matt Polizzotto, Travis Gannon and Wayne Robarge, as well as Rob Austin, Chris Niewoehner,
Allison Sams, Kim Hutchison, Matthew  Jeffries and Matt Church.

While the scientists had to base their first study on assumptions about the soil concentrations of trace elements – often called heavy metals – before the spill occurred, the second study began with collecting more than 500 soil samples along with more than 200 crop-tissue samples. That sampling gave the researchers a much more precise picture of the background concentrations of 13 trace elements at different locations along a 30-mile stretch of the Dan River.

Over two years, with Duke Energy funding, Hesterberg and his crew will be continuing to sample both soils and crops to get an idea of whether the levels are changing, what those changes mean for the farmers’ crops and livestock and whether the changes can be linked to the spill.

Hesterberg, who spends most of his time focusing on molecular-level soil chemistry, said that he found being able to apply his expertise to address such a pressing practical concern particularly rewarding. And Strader noted that the farmers were grateful to have the answers they needed to sustain their livelihoods.

Strader, now serving as county Extension director for Rockingham County, continues to be involved in community recovery efforts following the spill. As he put it, “There was a lot at stake here.”

“Because of the study,” he said, “farmers along the Dan River found comfort in knowing that they could plant and irrigate their crops and that millions of dollars of farmland could remain productive in agriculture. And in an area where agriculture is the No. 1 industry, that’s important for everyone.”

– Dee Shore