To protect human health and the environment, we need safe levels of per- and polyfluoroalkyl substances (PFAS) in our waters. Safe levels means water can be used for drinking, fish are edible, swimming and boating are safe, and aquatic life is supported.
Minnesota has been monitoring for PFAS in fish since the early 2000s. Based on current understanding, PFOS (perfluorooctane sulfonate) is the main PFAS of concern present in fish tissue. Levels of PFOS in fish tissue build up through the food chain from the fish’s intake of water and of organisms that have PFOS in them (like bugs). Concentrations of PFOS can be more than 7000 times higher in fish tissue than the surrounding water.
While PFOS has been measured at low levels in fish statewide, higher levels have been found some areas. The MPCA is using new science and information to update responses to PFOS in metro area water bodies that have the highest levels.
MPCA and MDH are setting goals for some PFAS levels. MPCA published new PFOS protective values for fish consumption (called “site-specific water quality criteria”) related to fish tissue and surface water value in 2020:
- The value for fish tissue is a maximum 0.37 nanograms PFOS per gram (ng/g) in fish tissue
- The value for water is a maximum 0.05 ng/L PFOS in water
Additional PFAS water quality criteria, including for PFOA, were published in January 2023 for the same waterbodies; details are found on the site-specific water quality criteria webpage.
These are not statewide standards. These are targeted site-specific water quality criteria for Lake Elmo (new values) and connected waterbodies, Bde Maka Ska, and Pool 2 of the Mississippi River (updates of values that are more than 10 years old for PFOS and PFOA).
We cannot clean our way out of this problem. The sustainable, longer term solution is to remove PFAS use in products and industrial processes before it gets into our water. The MPCA, MDH and DNR are committed to a long-term, holistic approach to dealing with PFAS. MPCA anticipates future actions using the site-specific water quality criteria framework, and may turn to rulemaking for aquatic consumption or to protect the aquatic community itself.
The MPCA is also working with permitted dischargers, such as wastewater treatment plants, to reduce levels of any PFAS in their discharge water. Many facilities are conduits of PFAS to the environment rather than sources that generate it. PFAS treatment is expensive and we know creative solutions and tools like variances may be needed.