Online predictions for stream concentrations of atrazine, one of the most
heavily used herbicides in the United States, are now available as
interactive maps and graphs for any stream across the country.

Access the online mapping tool, USGS report, and technical announcement at:
<http://water.usgs.gov/nawqa/> http://water.usgs.gov/nawqa/ under Featured
Highlights.

The predictions are based on a USGS statistical model - referred to as
Watershed Regression for Pesticides (or "WARP"). This model also provides
key statistics for each selected stream, including the probability that
atrazine may exceed a water-quality benchmark of potential concern, and a
level of confidence and uncertainty associated with each estimate.

This release is the first in a series of statistical models for atrazine and
other pesticides. The models are based on monitoring in 112 streams from
1992-2001, as well as watershed characteristics that affect the occurrence
of pesticides in streams, The driving characteristics include  agricultural
pesticide use, and natural features, such as soil characteristics,
hydrology, and climate. Current models make predictions from estimated
atrazine use during 2007.

Lead contact for questions: Bob Gilliom, rgill...@usgs.gov, 916-278-3094.