web-based pesticide contamination modeling (fwd)

Victor Guest vic at daena.eepo.com.au
Thu Jun 11 10:35:42 EDT 1998

rom: "John Vickery" <jvickery at iatp.org>
To: Multiple recipients of list <ag-impact at freedom.mtn.org>

I would like to bring Ag-Impact subscribers' attention to a website for
web-based water contamination modeling in row crops in Indiana.  

Contaminant focus: pesticides (also, nutrients)

Environmental compartment focus:  water (ground and surface)

Computer model:  NAPRA (National Agricultural Pesticide Risk Analysis),
developed by the USDA Natural Resources Conservation Service
(NRCS),Amherst, MA. (Incorporates GLEAMS)

Users can do a run on line, by going through entry forms and
indicating/selecting quite a number of parameters (soil type, types and
amounts of inputs and method of application, dates of field operations,
etc.)  Only about 55 pesticides are among those that can currently be

It takes a few minutes to do the inputting, a couple minutes to do the run,
and a long, long time to do the interpretation--the amount and multiplicity
of outputs (including graphs) is   overwhelming.  I have seen succinct,
tabular NAPRA outputs for pesticides in hard copy format that were quite
usable and readily interpretable (a sample output from my state NRCS
office), but wasn't able to find such among the output options at this web
site.  But then, I've only spent an hour on it so far, so . . . 

URL: http://danpatch.ecn.purdue.edu/~napra/nutrient.html  [site is under

(Available at

Note that NAPRA is the NRCS's "2nd tier" (i.e., currently the best
available ) pesticide impact assessment tool.  It provides quantitative
outputs (the percentage of an application that is predicted to run off the
edge of the field or leach below the root zone).

I am using the NAPRA team's "1st tier" pesticide impact assessment tool,
the Windows Pesticide Screening Tool (WinPST, aka Soil-Pesticide
Interaction Screening Procedure).  This is a qualitative method.  In the
near future, I'll post more information about WinPST and how I'm using it.

The following article (a popularized description) on the project appeared
in the 5/22/98


john vickery,
ag-impact adminstrator


"Computers, GIS Help Prevent Ground Water Contamination"

Surrounded by computer screens and hard drives, Bernie Engel creates and
analyzes digital images to protect Indiana's ground water. 

The Purdue agricultural engineer combined a computer model with geographic
information systems (GIS) satellite data to develop a plan to keep
agricultural chemicals out of the ground water that 60 percent of Indiana
uses for drinking water. Engel received the 1998 Research Award from the
Purdue School of Agriculture on May 6. 

His data base and program are the first to pinpoint potential water
problems field-by-field, and the first of their kind on the Internet
(http://danpatch.ecn.purdue.edu/~napra/nutrient.html). The Web site, still
is under construction, will ultimately tell pesticide users how much
chemicals they can safely use in all of their fields. 

The Office of the Indiana State Chemist used Engel's system to write
Indiana's pesticide management plan. It identifies and protects water in
areas that are considered most at risk of pollution from chemical spills or
from excess pesticides or fertilizers. Other states are modeling their
plans after Indiana's, Engel says. 

Engel's methods also are being used by NASA, the U.S. Army, the USDA
Natural Resources Conservation Service, and the EPA. 

Ground water pollution prevention is key, Engel says, because after the
damage is done it's so difficult to undo. "Once it's contaminated, it's
almost impossible to clean up," he says. 

>From the start, Engel has worked with the Indiana Department of
Environmental Management (IDEM) and the state chemist, because he wants his
research to meet their needs, as well as farmers' needs. 

Both agencies were eager to work with him after analyzing ground water data
assembled in 1995 by the U.S. Geological Survey, EPA and the Indiana
Department of Natural Resources. Those studies found 18 pesticides and five
pesticide breakdown products in 9 percent of the samples. Half the sampled
wells had nitrate levels above 2 parts per million (ppm)--below the EPA
action level of 10 ppm, but still a concern. The state was poised to act. 

"A regulatory approach didn't make economic or environmental sense," Engel
says. Across-the-board bans of certain pesticides can punish farmers who
could otherwise use those chemicals without risk to the environment. They
also force regulatory agencies to pay to monitor all ground water, rather
than focusing on water that is most at risk. 

"Monitoring is the most costly component of the State Management Plan,"
says Indiana state chemist Alan R. Hanks. "And it can only be decreased
based on a clearly established picture of the vulnerability of ground water
to contamination." 

Some ground water isn't at risk for contamination. For instance, some soils
bind chemicals before they can reach ground water, or the water table may
be so deep that pollutants likely won't reach it. However, other areas are
accidents waiting to happen. Before Engel's research, state agencies had
trouble finding potential problem areas. 

Using an existing as well as an updated computer model and GIS data, Engel
analyzed detailed data on the state's geology, watersheds, soil types,
climate and more. Engel's analysis enabled state agencies to target
potential ground water hot spots. 

To be sure his predictions would hold water, Engel compared them to nitrate
and pesticide measurements in statewide well water samples. It was more
accurate than any previously used technique. 

Engel's model indicates 75 percent of detectable pesticides in ground water
come from 25 percent of farmland, land where monitoring efforts are now
being focused. "It is now possible to gain significant savings by
concentrating the most intense monitoring efforts in truly vulnerable
areas," Hanks says. 

John Vickery, Senior Associate
     Environment and Agriculture
Institute for Agriculture and Trade Policy
2105 First Ave., S., Minneapolis, MN  55404-2505   USA
612-870-3430; FAX -4846    jvickery at iatp.org

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