BDC Magazine - Online version December 2015 Issue - 216 | Page 113

Electric News.qxp_feature 2 15/10/2015 15:50 Page 111

Innovative
Pesticide
Detection

A

new interactive mapping tool created by

than 50% probability that one or more pesticides exceed

the US Geological Survey provides pre-

aquatic-life benchmarks.

dicted concentrations for 108 pesticides in

The online mapping tool is based on a USGS statistical

streams and rivers and identifies which

model — referred to as Watershed Regression for Pesticides

are most likely to exceed water-quality

(WARP) — which provides key statistics for thousands of

guidelines for human health or aquatic life.

streams, including the probability that a pesticide may exceed a

The tool allows users to create maps showing where pes-

water-quality benchmark and the reliability of each prediction.

ticides are likely to occur in local streams and rivers and eval-

The WARP model estimates concentrations using informa-

uate the likelihood of concentrations exceeding water-quali-

tion on the physical and chemical properties of pesticides, agri-

ty guidelines. The predictions can also be used to design

cultural pesticide use, soil characteristics, hydrology, and climate.

cost-effective monitoring programs.

The model used by the mapping tool is based on data

“Because pesticide monitoring is very expensive, we can-

from USGS monitoring of pesticides in streams across the

not afford to directly measure pesticides in all streams and

USA since 1992 as part of the National Water-Quality

rivers,” said William Werkeiser, USGS Associate Director

Assessment (NAWQA) Program.

for Water. “This model can be used to estimate pesticide lev-

Since 1991, NAWQA has been a primary source of

els at unmonitored locations to provide a national assess-

nationally consistent data and information on the quality of

ment of pesticide occurrence.”

the nation’s streams and groundwater.

“The USGS pesticide model is a valuable tool that we can

Interactive mapping of predicted pesticide levels for

use, along with other modeling and analytical tools, to eval-

streams in the U.S. are available online. National maps and

uate data as we complete ecological risk assessments for pes-

trend graphs of agricultural use of 459 pesticides from 1992

ticides,” said Dr. Donald J. Brady, Director, Environmental

to 2012 are also available online.

Fate and Effects Division, Office of Pesticide Programs, U.S.
Environmental Protection Agency.

The pesticide-use maps show the geographic distribution of
estimated use on agricultural land in the United States for numer-

Wes Stone, USGS hydrologist and lead developer of the

ous pesticides. Maps were created by allocating county-level use

model said that streams and rivers most vulnerable to pesti-

estimates to agricultural land within each county. A graph accom-

cides can be assessed, citing the example of many streams in

panies each map, which shows annual national use by major crop

the Corn Belt region which are predicted to have a greater

for the mapped pesticide for each year during the period.