On 7/20/16 5 additional samples were taken at various lake locations. This time we tested for “total coliform” bacteria which are present in the digestive track of all warm-blooded animals. At all 5 locations, the results were 10 or less “colony forming units”/100 ml of water. To put this in perspective, the technician who did the tests at Life Sciences Laboratory in Wayland said that these results were better than a lot of the beaches they do tests for. The previous tests (summarized below) were for E.Coli. E. Coli are a subset of coliform and the tests cost $60 per sample ($300 total) as opposed to the coliform test which cost $50/sample (total $250). Fortunately the coliform tests came back low, so we are assured that the tests for E. Coli would have been even lower – and much improved from previous tests.
Three more water samples were taken on 8/31/15 and were tested for E. Coli.
A repeat test was run at the Rt. 21 creek outlet (by Meyer’s farm) since the 7/20/15 test result was 210 colony forming units (cfu)/100 ml which was quite high. The 8/31/15 sample tested at 5 cfu/100 ml. Since the 7/20/15 test was taken only a few days after a second heavy rain, this would indicate that closely spaced heavy rains do wash considerable E. Coli into the lake.
The southeast canal inlet and a location close to Joe Carlson’s water intake buoy were also sampled and both samples came back at 10 cfu/100 ml.
Apparently almost all lakes and streams have some E. Coli in them and the 10 cfu/100 ml value is on the low side. However, the standard for drinking water is 0 cfu/100 ml, so all lake and stream water needs to be treated to kill the E. Coli before drinking.