San Diego County. He also proposed that farmers would pay a $1 surcharge for every acre-foot of Colorado River water they use over the next 35 years. Urban users, who use less river water, would pay a $3 fee per acre-foot. The millions generated would cover the cost of new wetland habitats as well as air quality and Salton Sea mitigation associated with the water transfer to San Diego. References Colorado River History of Colorado Mexico–United States relations 1944 in Mexico 1974 in Mexico