I shook my head.

"It's when a factory pumps water in from a river and then pumps it back out, only the water is room temperature now, ten or twenty degrees warmer," he said. "It kills all the fish. You need a license to do it these days. It's so wonderful because, you see, it's just water. Pump it in, pump it out. What damage could that do? But it changes everything. Everything."