Testing Results After Two Months

Even though the State does not require it, we are continuing to measure the herbicide residue after it was measured as less than 75 parts per billion, and the State declared the lakewater to be “safe to drink*.”  We only sampled from two locations, because the cost of analyzing each sample is in excess of $100.00.  We chose the two locations where we had found the highest concentrations of triclopyr in earlier tests, one from each end of the lake.

As expected, the concentration has declined significantly.  Although the sites tested are where the chemical was applied, we believe that by this time the chemical has diffused throughout the lake, and that concentrations measured anywhere would be similar.

Location Applied June 3rd June 9th June 15 June 21 June 28 July 28
0 days 1 day 7 days 13 days 19 days 26 days 56 days
Site 1 1.5 ppm 202 ppb 121 ppb n/a n/a 38 ppb n/a
Site 2 1.5 ppm 930 ppb 127 ppb n/a n/a 66 ppb 13 ppb
Site 3 1.5 ppm 510 ppb 113 ppb 98 ppb 59 ppb 50 ppb n/a
Site 4 2.0 ppm 85 ppb n/a n/a n/a 47 ppb n/a
Site 5 2.0 ppm 160 ppb n/a n/a n/a 39 ppb n/a
Site 6 2.0 ppm 145 ppb n/a n/a n/a 42 ppb n/a
Site 7 2.0 ppm 123 ppb n/a 93 ppb 65 ppb 42 ppb 17 ppb
Site 8 2.0 ppm 332 ppb n/a 88 ppb n/a 40 ppb n/a
Site 9 0.0 15 ppb n/a n/a n/a 30 ppb n/a
Site 10 0.0 n/a n/a 31 ppb n/a 0.0 ppb n/a

We plan to test the water at least once more, in late August, around 12 weeks after the chemical application.

* The State has determined that 75 ppb is a safe amount of triclopyr in drinking water.  Nonetheless we do not recommend drinking from the lake – for a variety of other reasons.