Pesticides found in ND surface water
The recently released 2010 surface water monitoring study shows that four pesticides were detected in the water in southwest North Dakota.
The North Dakota Department of Health and U.S. Geological Survey conducted the survey, taking water samples from 33 sites from April through October.
"We do it as a favor for the U.S. Department of Agriculture," said Mike Ell, environmental scientist with the North Dakota Department of Health water quality division. "After we collect the samples the ag department sends them to an independent consultant for testing."
Jim Gray, director of the USDA Pesticide, Feed and Fertilizer Division, said all pesticide detections and concentrations were below levels deemed harmful by the Environmental Protection Agency.
"Results show that North Dakota's streams and rivers have minimal pesticide contamination," Gray said.
Last year's study had the second highest number of pesticide detections since the USDA began coordinating surface water studies in 2006.
A pesticide known as 2,4-D was detected both in the Knife River south of Hazen in June, and in the little Missouri River near U.S. Highway 85 in September.
The second chemical detected in June in the Knife River south of Hazen was dicamba.
MCPA was detected in Spring Creek near Zap in Dunn County.
"The chemicals detected are all used for weed control in crops and pastures," Gray said.
He added, none of the chemicals were found in concentrations high enough to affect human or aquatic health, but the last chemical, metolachlor, is a concern.
Metolachlor was detected in the Little Missouri River at Medora.
Metolachlor is used primarily on corn in North Dakota for grass and broadleaf weed control.
Metolachlor detections across the state ranged from .39 to .91 parts per billion. The aquatic life benchmark for metolachlor is 1 part per billion.
"These concentrations were approaching the 1 part per billion benchmark established for chronic invertebrate exposure," Gray said. "This could indicate a risk to aquatic life due to metolachlor use in North Dakota."
He added because the detections of metolachlor found in North Dakota were less than the concentration that had no effect on the water fleas, the department has concluded that metolachlor is currently only a minor concern.
"Metolachlor will continue to be monitored," Gray said. "Although no risk mitigation measures will be evaluated for metolachlor at this time."
According to the report, there were no reports of use of this chemical in Billings County or counties downstream in 2008.
The report estimates that the results could reflect an expansion of areas that grow corn from the previous survey.
Under a cooperative agreement with the EPA, the USDA is charged with regulating pesticides in the public's interest to ensure that they do not pose a risk of unreasonable adverse effects to human health or the environment.
North Dakota Agriculture Commissioner Doug Goehring said the results of the study shows that regulations, restrictions and the North Dakota Department of Agriculture's enforcement strategy are effective in preventing the contamination of surface water.