Pesticides and Degradates Widely Detected in USGS Chesapeake Bay Study

(Beyond Pesticides, March 3, 2008) In a five-year study of the Chesapeake Bay, the nation’s largest estuary, the U.S. Geological Survey (USGS) found that, “Synthetic organic pesticides and their degradation products have been widely detected at low levels in the watershed, including emerging contaminants such as pharmaceuticals and hormones.” The report finds that concentrations of DDT, while still present, have declined since the 1970s when it was phased out. The findings are contained in a report entitled Synthesis of U.S. Geological Survey Science for the Chesapeake Bay Ecosystem and Implications for Environmental Management. The study is a part of the Chesapeake Bay Program (CBP), which is a multi-agency partnership working to restore the Bay ecosystem.

According to the report introduction, “In 2005, which represented the mid-point of the Chesapeake 2000 agreement, there was growing concern at all levels of government and by the public that ecological conditions in the Bay and its watershed had not significantly improved. The slow rate of improvement, coupled with the projected human-population increase in the Bay watershed, implied that many desired ecological conditions will not be achieved by 2010. The Government Accountability Office (2005) recommended that the CBP complete efforts for an integrated assessment approach of ecosystem conditions and develop a comprehensive, coordinated implementation strategy. To address these challenges, the CBP partners are writing a strategic implementation plan (SIP) to more accurately define the degree to which restoration goals can be achieved by 2010, and the most effective approach to achieve the goals. The USGS findings and their implications provide critical information that will be used by the CBP partners to prepare the SIP and develop improved management strategies. A major CBP restoration goal is to “Have a “toxics free” Bay to improve conditions for aquatic-dependent wildlife.” As a part of this effort, the study seeks to define the occurrence of contaminants in the Bay watershed. Some of the
findings include:

  • Pesticides are present year round in streams of the Bay watershed.
  • Changes in pesticide concentration over time generally reflect changes in application rates, as well as physical and chemical properties that control the movement of compounds.
  • The following pesticides and degradation products were found in one or a combination of headwater streams during spring base flow, shallow ground water in agricultural areas, ground water used for domestic supply and ground water used for public supply: acetachlor, acetochlor ESA, acetochlor DA, alachlor, alachlor ESA, alachlor DA, atrazine, deethylatrazine, desiopropylatrazine, bromacil, carbofuran, cyanazine, dieldrin, flumetsulam, glyphosate, imazaquin, imazethapyr, lindane, metalachlor, metolachlor ESA, metolachlor DA, pendimethalin, prometon, simzaine, tebuthiuron.- Pesticide occurrence is closely tied with nutrient land practices on agricultural and urban lands.

In a national study of emerging contaminants which included the Bay (2002), at least one of 95 different emerging contaminants (including human and veterinary drugs, hormones, detergents, disinfectants, insecticides, and fire retardants) were found in 80 percent of the nation’s streams, “with mixtures of the chemicals occurring at 75 percent of the sites.”

In 2006, the U.S. Geological Survey (USGS) released Pesticides in the Nation’s Streams and Ground Water, 1992-2001, a ten-year survey of the contamination caused by pesticide use in agricultural and urbanized areas. Every year, nearly one billion pounds of pesticides, many of which are linked to cancer, birth defects, neurological disorders, and environmental impacts, are used in the U.S, much of it ending up in our nation’s waterways. The report is summarized in Beyond Pesticides’ Daily News Blog.

Two years earlier, according to Water Quality in the Nation’s Streams and Aquifers-Overview of Selected Findings, 1991-2001, released in 2004 as a compendium of 51 USGS reports on the health of major river basins across the country, insecticides such as diazinon and malathion were found in nearly all of the streams that were sampled in urban areas. Streams in agricultural areas were more likely to contain herbicides-especially atrazine, metolachlor, alachlor, and cyanazine.