BMPs have reduced atrazine runoff

Use of best management practices has significantly reduced atrazine concentrations in surface water reported Richard Fawcett, Fawcett Consulting, in a draft report released last week.

"Concentrations of the chlor-s-triazine herbicide atrazine have declined in U.S. surface water during a period when widespread usage continued,” Fawcett wrote.

He provided several examples from outside sources of reduced atrazine runoff and management practice changes:

• Atrazine concentrations in Rathburn Lake formed with construction of a dam on the Chariton River declined by 85 percent from 1996 to 2010.

• U.S. Geological Survey reported a 61 percent decline in atrazine concentrations in Midwestern rivers from 1989 to 1998.

• Atrazine concentrations in untreated water from a total of 103 community water systems using surface water declined “significantly” from 1994 to 2006.

• Agriculture Department Natural Resources Conservation Service has concluded soild conservation practices alone have resulted in a 51 percent reduction in atrazine loads in the Mississippi River.

• Data from rain runoff studies during nine site-years show runoff of atrazine and simazine was 75 percent of the runoff compared with moldboard plowed ground.

• In 18 filter strip studies, atrazine retention averaged 68 percent.

• Mechanical incorporation of atrazine showed an average runoff reduction of more than 50 percent.