The U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program sampled 37 urban streams throughout the United States for volatile organic compounds (VOCs) from 1995 to 2003. These urban streams were selected to (1) characterize stream water quality from areas draining predominantly residential and commercial land uses and (2) determine which natural and human factors affect stream quality. Initial interpretation of the VOC data set is focused on determining which VOCs commonly are found, the range of concentrations, and the temporal distribution (Lopes and Price, 1997).
The 37 urban streams sampled had drainage areas that ranged from 23 to 13,000 square kilometers with a median of 71 square kilometers. The urban streams are located in eight major surface-water regions within the conterminous United States, Alaska, and Hawaii. The urban streams were sampled for VOCs monthly for about 1 year with some storm samples collected at selected sites (Lopes and Price, 1997). A total of 869 samples (410 samples in the warmer months and 459 samples in the cooler months) were collected and were analyzed for 85 individual VOCs. Data are available at http://infotrek.er.usgs.gov/pls/nawqa/nawqa.home