AbstractDissolved mineral salts (salinity) adversely affects numerous urban and agricultural users of Colorado River water in southwestern United States and in Mexico. More than a third of the salt load is thought to be induced by drainage from irrigated lands onto highly saline groundwater deposits in the Upper Colorado Basin in Colorado, Utah, and Wyoming. Various public policy initiatives are proposed to induce farmers to reduce discharges of this nonpoint pollutant. Taxes on water, water conservation subsidies, and land and water rights purchases are analyzed in a linear programming framework. The allocative efficiency and the distribution of control costs and damages among irrigators, water users, and taxpayers are assessed.