RIVERS IN CORN BELT SEE DECLINE IN PESTICIDE LEVELS

News Date November 17, 2009

This past week, the U.S. Geological Survey issued a new report stating major pesticides concentration levels have either decreased or stayed the same from 1996 to 2006 in the corn belt rivers and streams.  

The authors of the report cite EPA regulatory actions along with new pesticide products leading to the decrease in concentrations of the agricultural herbicides cyanazine, alachlor and metolachlor. 

According to Skip Vecchia, senior author of the report on this analysis, “The steeper decline in these instances may be caused by agricultural management practices that have reduced pesticide transport, but data on management practices are not adequate to definitively answer the question.  Overall, use is the most dominant factor driving changes in concentrations.”

The corn belt region has among the highest pesticide use in the nation which is mostly herbicides used in weed control for corn and soybeans and found in the region’s rivers and streams.  High concentration levels can affect aquatic organisms as well as the quality of drinking water in high-use areas. 

“Pesticide use is constantly changing in response to such factors as regulations, market forces, and advances in science,” said Dan Sullivan, lead scientist for the study. “For example, acetochlor was registered by the EPA in 1994 with a goal of reducing use of alachlor and other major corn herbicides — acetochlor use rapidly increased to a constant level by about 1996, and alachlor use declined.”

Simizine, used for both agriculture and urban weed control, is the only herbicide that increased from 1996 to 2006. The increased concentration of simizine in some streams suggested that non-agriculture uses for controlling weeds in residential areas were higher than its trend in agriculture production.

Additional information can be found at the USGS Pesticide National Synthesis Project website.  (By: Preston Asay, Contact: Nathan Bowen)