This paper develops a simple, incentive compatible, allocation mechanism by means of which both polluters and pollutees will reveal their preferences so that the government can determine the Pareto optimal pollution level. The mechanism involves a combination of the Pigou tax and the Clarke tax. The two taxes are complementary and together provide a practical solution to the environment problem. The mechanism is applied to the problem of finding the optimal quality of river water that serves both as a waste disposal and as a source of drinking water. Copyright 1993 by Kluwer Academic Publishers
