Coal slurry is the contaminated process water that is leftover from the coal washing process. It contains elevated levels of chlorides, sulfates, arsenic, lead, mercury, and selenium. Really instead of "pond" toxic lake would be a better term. The black mountains are coal ash, the solid byproduct leftover after coal is burned to generate electricity. Coal ash contains elevated levels of arsenic, mercury, selenium, chromium and cadmium. Here at Crown III they take-in ash from 37 different sources, both in-state and out-of-state, and dump it in this unlined, above-ground impoundment.