A study conducted by the University of Minnesota Department of Civil, Environmental and Geo-Engineering and the Department of Natural Resources of Minnesota found high levels of insecticide in springs and some groundwater around Minnesota, according to a press release from the College of Science and Engineering on Nov. 18.
These insecticides could impact drinking water for individuals who tap their own water from surface-level wells or who drink directly from natural springs, said Bill Arnold, a University professor and the principal investigator of the study.
City and municipal wells are less likely to be contaminated because they tap water much deeper in the ground, Arnold said.
There are two types of groundwater — confined and unconfined groundwater, Arnold said.
“Unconfined groundwater is connected to the surface in some way, and then confined groundwater has some geologic layer between the surface,” Arnold said. “So that water tends to be older, it tends to be deeper. And that’s the stuff we often tap for drinking water.”
Unconfined groundwater is generally used for irrigation, Arnold said. The run-off of that water can end up in natural springs.
Arnold said people should avoid drinking directly from natural springs because of this.
“People who think that, ‘Oh, I’m going to a natural spring to get water because it’s natural, it’s flowing from the ground. It’s got to be safe,’” Arnold said. “Depending on where you are in the state and where, what the connectivity of that spring is, I’d say you’re much more likely to get contamination in a spring than you would in a well.”
Arnold said most of the contaminated water was found in the Minneapolis-St. Paul area and the Karst Region in southeastern Minnesota.
In an email to the Minnesota Daily, the Minnesota Pollution Control Agency (MPCA) said they will use the results of the study to inform how they approach maintaining clean drinking water.
“The MPCA appreciates recent research conducted by the University of Minnesota and the Minnesota Department of Natural Resources that found high concentrations of insecticides in some of the state’s ground and surface water,” said Michael Rafferty, the spokesperson for MPCA. “Information from this study can be incorporated into strategies that MPCA and its state partners develop to protect and restore water quality in both ground and surface waters.”
Insecticides end up in springs and shallow groundwater through the run-off of crops being treated but also by people using those same chemicals on their own plants at home, Arnold said. Because the chemicals are used both in agricultural and urban settings they showed up more in areas of the state where one of those attributes is prominent.
“We put them out in the environment, and they’re relatively water-soluble, and so then they get transported when water flows,” Arnold said.
Arnold said there are a few ways to prevent insecticides from ending up in water. One way is to design chemicals that are more degradable. He added another way is to use them less frequently.
“We certainly over-apply them in all sorts of scenarios,” Arnold said. “Making sure that you’re using them when it’s needed and not is a preventative measure a lot of times as well.”
Small changes like these can help deter the amount of insecticides that end up in springs and groundwater, Arnold said.
