The Minnesota Department of Public Health (MDH) and Pollution Control Agency (MPCA) work together to investigate and mitigate the presence of PFAS in drinking water in both private wells and sources of supply for municipal systems throughout the state.
Their investigation of PFAS in Minnesota’s sources of drinking water began in 2002 when a release into groundwater from manufacturing and waste disposal sites east of the Twin Cities was identified. In response, MDH has established health-based values for several species of PFAS including PFOS, PFOA, PFBA, and PFBS, and uses the PFOS health-based value as a “surrogate” value to evaluate PFHxS. This surrogate approach will continue until sufficient toxicological information is available to set a specific value for PFHxS. MDH also uses a weighted additivity calculation to evaluate drinking water (public or private) that contains a mixture of PFAS. As water quality testing methods improve and additional research is conducted on the health impacts of PFAS in drinking water, MDH adds values for additional PFAS species and updates existing criteria. Since there are currently no enforceable federal or state maximum contaminant levels for PFAS, these health-based criteria guide decisions about the mitigation of contaminated sites.
MDH and MPCA provide technical assistance to municipal system operators and private well users to employ diverse PFAS mitigation methods that are tailored to each unique set of circumstances. MDH also provides informational materials for the general public that explain MDH and MPCA’s available resources and programs, and a fact sheet on PFAS health risks. A complete history of MDH and MPCA’s actions to address PFAS (including a regularly-updated timeline that summarizes annual progress going back to 2002) is available online. Examples of some of these actions include:
- The city of Oakdale initially was able to lower PFAS concentrations to below health-based criteria immediately by limiting the use of their two most impacted wells and increasing the pumping rate from the least impacted wells. Approximately a year after PFAS detection, a new water treatment plant was operating to remove PFAS from water from those two wells and four years later a new clean well was drilled outside the impacted area.
- When PFAS are detected above health-based criteria in private wells, MPCA provides bottled water to residents using that well until a longer-term solution (treatment or connection to city water) can be put in place.
- Granular activated carbon filters are provided and maintained by MPCA for impacted private well users.
- The city of Lake Elmo expanded their water supply system infrastructure to give access to homes with contaminated private wells; other cities have assisted with connection of affected residents where water mains are already present.
- The MDH Well Management Section established the Lake Elmo-Oakdale Special Well and Boring Construction Area, creating special requirements for the construction, repair, modification and permanent sealing of wells and borings within the boundaries of the contaminated area and testing of all new wells for PFAS prior to their use for drinking water.
Minnesota residents who use private drinking water wells and are located within the MPCA sampling area can fill out an online well sampling request form if they are concerned about potential PFAS contamination. MDH prioritizes their responses based on the proximity of the well to known contamination sites. While most investigation and mitigation activities have taken place in the priority sampling area, which is outside of the Great Lakes basin, MDH and MPCA have also investigated other locations throughout the state with a potential for PFAS contamination. These include fire training facilities, chrome plating plants, waste water treatment plants, and landfills. Two of these investigations took place within the city of Duluth, along tributaries to Lake Superior. According to MDH, PFAS has been detected at many of locations outside of the priority sampling area, but only two other sites have had detections above health-based criteria in drinking water, both related to sites where PFAS-bearing aqueous film-forming foams (AFFF) were used at fire training facilities. The extent of impacts at these sites were much less extensive than in the east Twin Cities area.