Most of the arsenic in America's water is put there by nature. It is mostly in groundwater in rural, not industrial areas. And in rural jurisdictions with small tax bases, the Clinton standard might have increased water costs so much that people would have dug their own wells, thereby increasing their exposure to arsenic. For an introduction to such reasoning, try a new novel published, implausibly, by the MIT Press. Instructing his class in the unintended consequences of government interventions in complex systems, the young economist tells his class about the elimination of wolves from Yellowstone in the first half of the 20th century.
Wolves eat elk.
Intensified grazing by the exploding elk population stripped vegetation from the banks of streams, including willow and aspen that beavers need for food. The beaver population plummeted. Suppose you love pistachio nuts, and are given a room filled with them to a level of five feet. But you must eat them in the room, and must leave the shells. As it becomes increasingly difficult to find nuts amidst the shells, the nuts will not be free anymore.