How were NAWQA sampling sites selected?
NAWQA sampling sites are part of a “targeted” monitoring design that focuses on understanding the relations between water-quality conditions and the natural and human factors that cause those conditions. Monitoring sites are therefore not selected randomly within a grid, but because they represent certain human activities, environmental settings, or hydrologic conditions during different seasons or times of year. For example, sites may be selected to assess the effects of agriculture and urban development on pesticide and nutrient contamination in streams. Sampling locations for streams and ground water were selected or “targeted” to represent specific agricultural, urban, undeveloped, and mixed land-use settings of greatest significance to water resources in the primary hydrologic settings within each of the 51 Study Units. Sites were selected by local Study Unit teams in collaboration with local organizations, States, and Tribes, as well as NAWQA national teams. Streams and ground wa
