On Tuesday, June 15th, we collected four more samples, and sent them off for analysis. Today we received the results from the lab. They appear in the table below.
|location||Applied concentration||June 3rd||June 9th||June 15th||(future)|
|Site 1||1.5 ppm||0.202 ppm||0.121 ppm||n/a|
|Site 2||1.5 ppm||0.930 ppm||0.127 ppm||n/a|
|Site 3||1.5 ppm||0.510 ppm||0.113 ppm||0.098 ppm|
|Site 4||2.0 ppm||0.085 ppm||n/a||n/a|
|Site 5||2.0 ppm||0.160 ppm||n/a||n/a|
|Site 6||2.0 ppm||0.145 ppm||n/a||n/a|
|Site 7||2.0 ppm||0.123 ppm||n/a||0.093 ppm|
|Site 8||2.0 ppm||0.332 ppm||n/a||0.088 ppm|
|Site 9||0.0||0.015 ppm||n/a||n/a|
|Site 10||0.0||n/a||n/a||0.031 ppm|
The concentrations have not decreased as rapidly as we would like. We had hoped that the they might be down to 0.075 ppm, so that the next restriction might be lifted. The average concentration of triclopyr in the lake on Tuesday was 0.093 ppm, which is about 25% above this level.
The three results from the lake are all within a narrow range, which provides an internal indicator of reliability. The downstream concentration is low, less than half of the 0.075 ppm set by the State as “safe for drinking.”
We will decide soon when the next samples will be taken, and keep you informed here.