Monsanto Phosphate Plant and Slag Pour, Idaho

Monsanto operates a phosphate plant at this location that dumps glowing molten phosphate ore down the edge of its slag pile around 5 times an hour, 24 hours a day. The 530 acre plant has operated since 1952, and the slag mound is an elevated landscape, growing slowly at its edges, and is 150 feet high in places. The phosphate produced here is used in many products, including toothpaste, foods, cleansers, fertilizers, and herbicides. A number of large industrial complexes are in the valley, including Kerr-McGee Chemical Corp., directly across State Highway 34 from Monsanto.