Water-quality indices for specific water uses

Water-quality indices were developed to assess waters for two specific uses--public water supply and irrigation. The assessment for a spcific water use is based on the availability f (of (1) a set of limits for each water quality property selected, (2) a rationale for selection, and (3) information that permits one to appraise the relationship of the concentration of the selected property to the suitability of the specific water use. The selected properties are divided into two classes: Type-I properties, those normaly considered toxic at low concentrations, and type-II properties, those which affect aesthetic conditions or which at high concentrations can be considered toxic or would otherwise render the water unfit for its intended use. (Woodard-USGS)