In the early 1940s, Stevens County buried roughly 1,500 pounds of arsenic-based grasshopper pesticide in a gravel pit about one mile northeast of Morris, Minnesota. The Minnesota Department of Transportation later built U.S. Highway 59 through that same gravel pit in 1978. EPA added the site to the Superfund National Priorities List in September 1984 after detecting traces of arsenic in soil and groundwater.
Arsenic is the only contaminant of concern at this site. It was found in both soil and groundwater. Because arsenic occurs naturally in glacial deposits across western Minnesota, and because it was widely used in grasshopper bait during the 1930s and 1940s, investigators could not confirm whether the arsenic came from the buried pesticides or from natural background sources. Measured concentrations fell within natural background levels for the region. Arsenic is a known carcinogen and can cause non-cancerous illnesses or death, but the levels at this site do not pose a health hazard to the public.
EPA completed a remedial investigation and feasibility study beginning in March 1984. The agency selected a "no action" remedy in August 1985, meaning no physical cleanup was required. The site was deleted from the National Priorities List in March 1986. EPA has determined that human exposure is under control and that contaminated groundwater migration is stabilized with no unacceptable discharge to surface water. EPA will continue monitoring to confirm the groundwater stays within the original area of contamination.
Institutional controls remain in place to limit land uses and reduce potential exposure. These include zoning restrictions that prevent residential development inconsistent with the site's cleanup level. The site achieved sitewide ready for anticipated reuse status in August 2009, meaning all cleanup goals for current and reasonably anticipated future land uses have been met. The Minnesota Department of Health recommends that any new drinking water wells in western Minnesota be tested for arsenic.
Community members with questions can contact the EPA's Community Involvement Coordinator or Remedial Project Manager. Three key documents related to the site are available through EPA's Superfund records system.
