Monitoring Herbicides in Midwest Drinking Water

Sampling of water running through the St. Joseph River watershed in northeast Indiana is showing glyphosate herbicide contamination to be minimal, according to Agricultural Research Service (ARS) studies. Glyphosate levels exceeded the federal limit for drinking water only once during three years of testing.

That’s good news to about 200,000 residents of Fort Wayne, Ind., and to some two dozen other small, rural communities that rely on this watershed for their drinking water.

However, three years of testing data from the ARS National Soil Erosion Laboratory (NSERL) at West Lafayette, Ind., show that atrazine herbicide is often found above the U.S. Environmental Protection Agency limit for drinking water. Drinking water treatment plants in the Fort Wayne metropolitan area use activated charcoal to remove atrazine that has most likely run off from cornfields. Atrazine is widely used to control weeds on Midwestern cornfields.

Since many farmers in the St. Joseph River watershed region must rely on drainage pipes and ditches to get their fields dry enough to plant, ARS supports a project focused on measuring--and curbing--runoff pollution from these drainage systems.

Runoff from farms carries nutrients and soil, as well as pesticides, to the St. Joseph River. Scientists involved with this watershed project are looking at a variety of drainage improvements, such as maintaining an even water table, adding alum or gypsum to reduce contaminant levels in runoff, and filtering standing water.

The ARS leader of this project, Chi-Hua Huang, also heads NSERL. That facility was recently converted into the agency’s newest water-quality lab. It’s the only lab involved in the U.S. Department of Agriculture’s new Conservation Effects Assessment Project (CEAP) that is sampling water for glyphosate (Roundup), the herbicide that’s increasingly being substituted for the older atrazine.

The NSERL has two automated systems with special extraction equipment that can simultaneously detect five different pesticides in tiny amounts of water.

The CEAP program is designed to make sure that taxpayers are getting their money's worth from publicly funded USDA conservation measures administered through the Farm Security and Rural Investment Act--the “Farm Bill.”

ARS is USDA’s chief in-house scientific research agency.