The usefulness of the waters of the Colorado River is impaired by its salinity. In recognition o f this and other interstate water quality problems, the Congress, in the Federal Water Pollution Control Act Amendments of 1972, called for the adoption of water quality standards for interstate waters. Pursuant to that mandate, the U.S. Environmental Protection Agency (EPA) on December 18, 1974, issued a regulation requiring the states of the Colorado River basin to adopt numeric criteria and a plan to implement salinity control. In response to this requirement, the states developed programs to control Colorado River salinity. Principal components of these programs are “studies of means to minimize salinity in municipal discharges.”