Contamination Areas

Groundwater Contamination

Groundwater in Washington County has contaminants above the established health risk limits in a number of aquifers. The contamination is generally of two types:
  • Contamination resulting from volatile organic or inorganic chemicals leaching from legal and illegal waste disposal and underground storage tanks
  • Contamination of nitrates in parts of the county resulting from certain land use practices and sensitive geologic conditions

Special Well and Boring Construction Area (SWCA)

The Minnesota Department of Health declared a Special Well and Boring Construction Area (SWCA), sometimes called a well advisory, for areas where contaminants are found at a level that poses public health risks. The purpose of a SWCA is to inform the public of potential health risks in areas of groundwater contamination, provide for the construction of safe water supplies, and prevent the spread of contamination due to the improper drilling of wells or borings. The SWCA designation provides for controls on the drilling or alteration of public and private water supply wells, and the monitoring of wells in the area. Washington County has four Special Well and Boring Construction Areas:
  • Lake Elmo/Oakdale
  • Baytown/West Lakeland Townships
  • Lakeland/Lakeland Shores
  • St. Paul Park/Newport
In Washington County, Minnesota Statutes, section 103I.236, states “Before signing an agreement to sell or transfer real property in Washington County that is not served by a municipal water system, the seller must state in writing to the buyer whether, to the seller’s knowledge, the property is located within a special well and boring construction area."

Go to the Minnesota Department of Health Special Well and Boring Construction Areas to learn more information about each site.

Perfluorochemical Waste

Perfluorochemical (PFC) containing wastes were disposed of by the 3M Company at the 3M disposal sites in Oakdale, Woodbury, and Cottage Grove, and the former Washington County Landfill in Lake Elmo. PFCs were released from the sites, resulting in contamination of groundwater and nearby drinking water wells.

Additional information on PFC contamination

For more information on recent changes to the EPA advisory levels for certain PFCs, and impacts to private wells in Washington County, please visit the MDH website. 80 new well advisories have been issued and sampling will occur in an additional 400-500 homes in the Fall of 2016. 

You can also view this interactive map to see if you may be in a priority sampling area.

VOC and PFC Testing in Contamination Areas

The Department of Public Health and Environment offers private well water testing for perfluorochemicals (PFCs) and volatile organic compounds, including trichloroethylene. Please go to the water tests page for more information.

In response to the EPA Health Advisory for PFOS and PFOA, and the need to prioritize sampling being conducted by MPCA and MDH, the county is suspending PFC testing until further notice.  

Nitrates in Washington County

Nitrates have also been found in private wells at levels that exceed the established health risk level of 10 mg/L. The majority of wells affected by nitrate contamination are found in Cottage Grove and Denmark township, though you can see high nitrates in other areas, from localized sources. See the link below for results of a recent private well testing study conducted by the Minnesota Department of Agriculture, in partnership with the county and the Washington Conservation District.

MDA Washington County 2014 Summary Report