Pesticides and Water Quality

Featured Study: Pesticides in Stream Biofilms

Featured Study: Pesticides in Stream Biofilms

Analysis of stream biofilms reveals the presence of a wider array of pesticides than analysis of bed sediment, reports a new study by the USGS Regional Stream Quality Assessment.

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Featured Study: Multiple Pesticides in U.S. Streams

Featured Study: Multiple Pesticides in U.S. Streams

A mix of multiple pesticides is common in many U.S. streams, reports a new study by the U.S. Geological Survey National Water Quality Program.

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Science Center Objects

Pesticides are chemicals designed to kill pests, including insects (insecticides), weeds (herbicides), and fungi (fungicides). The USGS assesses the occurrence and behavior of pesticides in streams, lakes, and groundwater and the potential for pesticides to contaminate our drinking-water supplies or harm aquatic ecosystems.

Pesticides are used in agriculture, in homes and businesses, on lawns and gardens, along roads, in recreational areas, and on pets and livestock. There are hundreds of different pesticide chemicals in use in the United States. In 2007, about 390 million kilograms (430,000 tons) of pesticides, including herbicides, insecticides, and fungicides, were used in the United States. Pesticides released into the environment for agricultural and nonagricultural purposes can contaminate surface water and  groundwater, which are critical sources of drinking water.

A national map that shows by color estimated concentrations of atrazine in shallow groundwater underneath agricultural land.

This map shows the predicted probability that the sum of concentrations of atrazine and its degradate deethylatrazine (DEA) will exceed 3.0 micrograms per liter (µg/L) in shallow groundwater underlying agricultural lands. Although shallow groundwater is unlikely to be used as a source of drinking water, the 3.0 µg/L threshold shown on this map is EPA’s drinking water standard (Maximum Contaminant Level) for atrazine.  About 95% of the nation’s agricultural areas have less than a 10% chance of exceeding this threshold. Atrazine is one of the most extensively used herbicides in the United States, with average annual use over 70 million pounds—primarily for corn and sorghum. (Credit: Paul Stackelberg, USGS)

The USGS, through its National Water Quality Program, researches numerous aspects of pesticides and water quality, and has developed maps, graphics, and tools to aid in understanding where pesticides occur, at what concentrations, and potential consequences.