Silver Bay, on the Minnesota shore of Lake Superior, became the center of pollution control lawsuits in the 1970s when cancer-causing asbestos-type fibers, released into the lake by a Silver Bay factory, turned up in the drinking water of numerous Lake Superior cities. While pollution lawsuits have become common, Silver Bay was a landmark case in which a polluter was held liable for probable, but not proven, environmental health risks. Asbestos, a fibrous silicate mineral that occurs naturally in rock formations across the United States and Canada, entered Lake Superior in the waste material produced by Silver Bay's Reserve Mining Corporation. This company processed taconite, a low-grade form of iron ore, for shipment across the Great Lakes to steel-producing regions. Fibrous asbestos crystals removed from the purified ore composed a portion of the plant's waste tailings. These tailings were disposed of in the lake, an inexpensive...