National Water-Quality Assessment (NAWQA) Program
The number of sites in NAWQA’s status and trends network totals 113 across the 8 major river basins.
Twelve of the current sites monitor conditions in large rivers that drain major agricultural and urban areas throughout the Nation. These sites represent predominant crops within each of the eight regions and urban centers in four of the regions. They include:
Potomac River at Washington, D.C.
White River at
Trinity River below
The remaining sites represent smaller urban or agricultural watersheds. NAWQA’s surface-water sites will have been monitored consistently for more than a decade, and therefore will be critical in determining trends in nutrients and pesticides. In addition, the sites will address specific issues, such as runoff and transport of nutrients and pesticides in urban areas, and the effect of soil type, irrigation, and artificial drainage on pollutant transport in agricultural areas.
The NAWQA monitoring network uses a rotational sampling scheme; therefore, sampling intensity varies year to year at the different sites.