Lake Elmo's well closure not a sign of things to come
WASHINGTON COUNTY — Though perfluorochemical levels in one Lake Elmo well forced the city to take it offline, south Washington County communities are not likely to face the same fate.
The Minnesota Department of Health has been conducting quarterly testing on wells nearing the health index they announced last May.
The health index is measured by the proportions of different PFC chemicals including PFOA and PFOS. If the value is above 1.0 for four consecutive quarters, MDH recommends that the city find a solution.
The Lake Elmo closures of a well and a water tower March 28 were due to these quarterly tests, and not from a notable increase in PFC water pollution, according to MDH environmental manager Jim Kelly.
For the most part the plume containing PFCs is steady, slow-moving and stable, not likely cause any extreme changes to water quality, according to MPCA Hydrogeologist Ginny Yingling.
One well in St. Paul Park has been above the health index for three consecutive quarters, and may need to be taken offline if it gets to the fourth. One of the city's three wells was above the limit last summer, and its water is blended with the other wells to keep it below the index.
If the second well is above 1.0, there may not be the option to blend water anymore, and the city will have to explore treatment options.
The test fourth quarter will be done this summer.
Kelly said the MDH isn't monitoring any other wells in the same way, so it is unlikely other wells will need to be taken offline in the near future.
Five Cottage Grove wells were briefly offline last summer, and three others were only available for limited use. Water has been below health index since the city added temporary granular-activated carbon filtration to two city wells last fall.
Kelly said for the most part the presence of PFCs in municipal water is trending downward.
PFOAs have been increasing slightly in both in Lake Elmo and St. Paul Park, while PFOS remain low in their wells.
The MDH decreased its health-based values from the 70 parts per trillion recommended by the U.S. Environmental Protection Agency to 35 ppt PFOA and 27 ppt PFOS last May.