On Thursday, June 3rd, 24 hours after we completed the chemical treatment of Lake Fairlee, we took nine water samples at designated locations around the lake and sent them to the lab for analysis. Because the lab will not start the 48 hour testing process on a Friday, the samples were submitted on Monday the 7th, and we just received the results today.
Sample sites one through eight are located around the lake in representative areas that received treatment. Site nine is almost a mile downstream, where the creek that flows out of the lake runs into the Ompompanoosuc. (map) The results (left column) range from .085 ppm to .930 ppm. All but two of the results were .332 ppm or below. No one has been able to explain just why two of the samples showed such high results, while the others were much lower.
The strength of the applied chemical was 1.5 ppm in the northeastern end of the lake, and 2.0 ppm in the southwestern. For some reason the average concentration found by the tests was higher in the end of the lake in which the applied concentration was lower. These are raw data and one can expect some variability in individual readings. Nonetheless the concentration found at site #2 seems much higher than we were led to believe it should be, and out of line with the other samples. We have asked the scientists with experience with these procedures for help understanding why there might be so much variation.
The immediate point of this testing is to let us know when we can lift the restriction on the use of lake water for drinking and preparing food. The State will allow us to remove that restriction when the concentration at every location tested is below 75 ppb (which is .075 ppm). We will keep you informed.
WARNING: Even when this restriction related to the treatment is lifted, we still do not think that drinking the water in the lake is safe, for a variety of other reasons.