2009 E. coli Sampling Results

In 2009, the WRP tested for E. coli at 26 sites throughout the watershed, every other week from June through September. Because E. coli counts can fluctuate dramatically depending on weather and other watershed inputs, the EPA recommends that a geometric mean (an average that evens out large variations in the data) be used instead of a simple average when considering multiple samples taken from the same site over time.

At the end of each sampling season, we calculate the geometric mean of E. coli at each site. This allows us to identify trends at each site over time. The EPA standard for the geometric mean is 126 colonies/100 mL sample. Sites that exceed the EPA standard are marked with an asterick (*).

E. coli Data, summer 2009

Main Stem sites

Watson Park – 105
West Hartford Bridge – 101
Mouth of Mill Brook – 45
White Brook – 150*
VLS Parking Lot – 108
Bethel below tx – 110
Bethel Bridge – 58
Peavine Park – 53
Mouth of Locust Creek – 13
Silver Lake – 4
Gaysville Bridge – 47
Tweed at South Hill Road – 43
Lion’s Club Park – Rochester – 33
Above Hancock Branch – 29

First Branch sites

Cilley Bridge – 82
Chelsea Rec Park – 79

Second Branch sites

Dugout Road – 144*
East Hill Road – 72

Third Branch sites

Mouth of Third Branch – 123
Stock Farm Road – 115
Golf Course Bridge – 112
Ayers Brook – 134*
Adam’s Brook – 15
Thresher Road – 66