Pesticides in Ground Water
U.S Geological Survey Fact Sheet FS-244-95
Current Understanding of Distribution and Major Influences
This report summarizes a comprehensive analysis of existing
information on national and regional patterns of pesticides in
the atmosphere and major influences on their sources and transport.
It is one of a four-part series that synthesizes current
knowledge and understanding of pesticides in water resources of
the nation as part of the National Water-Quality Assessment.
Bibliography of Studies Reviewed
- 974 References
Highlights
- Over 300 studies of pesticide occurrences in ground
water and soils have been carried out during the past 30
years.
- Pesticides from every major chemical class have been
detected in ground water.
- Pesticides are commonly present in low concentrations
in ground water beneath agricultural areas, but seldom
exceed water-quality standards.
- Little information is available on pesticide occurrence
beneath non-agricultural land, such as residential areas
and golf courses, despite application rates that often
exceed those for most crops.
- Frequencies of pesticide detection are almost always low
in low-use areas, but vary widely in areas of high use.
- Pesticide levels in ground water show pronounced seasonal
variablity in agricultural areas, with maximum values
often following spring applications.
- Factors most strongly associated with increased
likelihood of pesticide occurrence in wells are high
pesticide use, high recharge by either precipitation or
irrigation, and shallow, inadequately sealed, or older
wells.
Pesticides in Ground Water