Pesticides in urban and agricultural streams, 1993-95

Abstract

Nonpoint sources of pesticides are a national issue and are a major interest in the U.S. Geological Survey National Water-Quality Assessment (NAWQA) Program because of their potential toxicity to humans and aquatic life. Using the water-quality data collected by the Trinity River Basin NAWQA study-unit team, an analysis of pesticides in urban and agricultural streams was made by aggregating and grouping data from several networks. The samples were collected during March 1993 through September 1995. About 70 samples were collected from urban streams and 70 from agricultural streams. The urban dataset consists of sampling sites in the Dallas-Fort Worth metropolitan area where more than 3.5 million people lived in 1990. Land use in the sampled urban watersheds is primarily residential, but there are commercial areas, such as shopping centers and office complexes along major highways and streets. The agricultural dataset consists of sampling sites in the watershed of Richland-Chambers Reservoir, an area in the west-central part of the Trinity River Basin where fertile soils are extensively cultivated. The land use is mostly cropland and pasture with some rangeland. In the cultivated areas, the major crops are corn, cotton, and sorghum. In the rangeland areas, cattle are the dominant livestock. In the pasture areas, hay is grown along with grass for cattle feed. None of the crops are irrigated. The material in this fact sheet is condensed from a report by Land and Brown (1996) where the study is presented in greater detail.