BOKOSHE, OKLA.—On the edge of Bokoshe, population less than 500, sits a hill about 60 feet high, covered partly with soil. From a distance, it could be a natural part of eastern Oklahoma’s rolling hills. But this mound isn’t like the others: It’s made of toxic fly ash, a coal byproduct from electricity production, generated by power company AES. The fly ash fills in an unlined, abandoned strip mine at a site also used to dump wastewater from fracking. When it rains, the waste runs into nearby lakes and tributaries of the Arkansas River.

According to Physicians for Social Responsibility, fly ash contains a range of heavy metals, from arsenic to lead to mercury, some of which are linked to cancer.

Residents of Bokoshe have been trying to stop the pollution for years, only to meet with denial at the corporate and state levels. No one in power, it seems, will admit it’s a problem.

That hasn’t stopped Tim Tanksley, 73, a Vietnam vet born and raised in Bokoshe. He and his neighbors call their representatives, file complaints with the Oklahoma Department of Environmental Quality (ODEQ) and have appeared on state PBS affiliate OETA.