Pesticide Compounds in Streamwater in the Delaware River Basin, December 1998-August 2001

By R. Edward Hickman


U.S. Geological Survey Scientific Investigations Report 2004-5105


The body of the report is available in PDF Format (5826 KB)


During 1998-2001, 533 samples of streamwater at 94 sites were collected in the Delaware River Basin in Pennsylvania, New Jersey, New York, and Delaware as part of the U.S. Geological Survey National Water-Quality Assessment Program. Of these samples, 531 samples were analyzed for dissolved concentrations of 47 pesticide compounds (43 pesticides and 4 pesticide degradation products); 70 samples were analyzed for an additional 6 pesticide degradation products.

Of the 47 pesticide compounds analyzed for in 531 samples, 30 were detected. The most often detected compounds were atrazine (90.2 percent of samples), metolachlor (86.1 percent), deethylatrazine (82.5 percent), and simazine (78.9 percent). Atrazine, metolachlor, and simazine are pesticides; deethylatrazine is a degradation product of atrazine.

Relations between concentrations of pesticides in samples from selected streamwater sites and characteristics of the subbasins draining to these sites were evaluated to determine whether agricultural uses or nonagricultural uses appeared to be the more important sources. Concentrations of atrazine, metolachlor, and pendimethalin appear to be attributable more to agricultural uses than to nonagricultural uses; concentrations of prometon, diazinon, chlorpyrifos, tebuthiuron, trifluralin, and carbaryl appear to be attributable more to nonagricultural uses.

In general, pesticide concentrations during the growing season (April-October) were greater than those during the nongrowing season (November-March). For atrazine, metolachlor, and acetochlor, the greatest concentrations generally occurred during May, June, and July.

Concentrations of pesticide compounds rarely (in only 7 out of 531 samples) exceeded drinking-water standards or guidelines, indicating that, when considered individually, these compounds present little hazard to the health of the public through consumption of the streamwater. The combined effects of more than one pesticide compound in streamwater were not considered.

Diazinon appeared to be the pesticide compound most likely to adversely affect aquatic life in the streams of the Delaware River Basin; concentrations of diazinon exceeded guidelines (designed to protect aquatic life) in 19 samples, the most of any pesticide compound. Concentrations of as many as 5 compounds exceeded guidelines in 29 of 531 samples.




Purpose and Scope

Description of the Study Area

Design and Methods of Study

Streamwater Sampling Sites

Field Methods

Laboratory Methods

Quality Assurance/Quality Control Methods

Application Rates of Pesticides to Agricultural Land

Methods of Data Analysis

Pesticide Compounds in Streamwater in the Delaware River Basin

Summary of Detection Frequencies and Concentrations

Pesticide Compounds (Gas Chromatography)

Pesticide Degradation Products (High Performance Liquid Chromatography)

Bias and Variability of Detection Frequencies and Concentrations

Pesticide Compounds (Gas Chromatography)

Pesticide Degradation Products (High Performance Liquid Chromatography)

Relations Between Concentrations of Selected Pesticides and Indicators of Agricultural and Nonagricultural Uses of Pesticides

Variation in Concentrations of Selected Pesticides with Season

Relations of Concentrations of Selected Pesticides to Streamwater Turbidity

Comparison of Concentrations of Selected Degradation Products with Concentrations of
Parent Pesticides


Ethane Sulfonic Acid and Oxanilic Acid Degradation Products of Alachlor, Acetochlor, and
Metolachlor at Two Sites

Comparison of Concentrations of Pesticide Compounds to Standards and Guidelines for the Protection of Human Health and Aquatic Life

Human Health

Aquatic Life

Summary and Conclusions

References Cited


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