How are the sites selected for study?
In general, the community water systems are selected to meet several criteria. Specifically, sites are located in study areas previously sampled by the NAWQA Program during 1992-2001 where data on source water and treated water can be compared to other NAWQA data collected from streams across the country. The community water systems also are generally located on free-flowing reaches of streams. In addition, they are generally single-source systems, with little or no blending of other source waters and are relatively large (serving more than 10,000 people). The type of water treatment or prior monitoring results, including those for compliance monitoring, are not considered in the selection process.
