2007 E. coli Sampling Results

The WRP tests for E. coli at 26 sites throughout the watershed, for 13 consecutive weeks each summer. E. coli counts can fluctuate dramatically depending on weather and other watershed inputs. Because of this, 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 for the year. This allows us to identify trends at sites 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 2007

Main Stem sites

Watson Park – 29.9
Dimick Brook – 53.4
Mill Brook – 30.6
Sharon – 105.3
Payne’s Beach – 99.4
Fox Stand – 131.4*
Bethel – 89.3
Bethel Bridge – 47.2
Mouth of Locust Creek – 67.3
Silver Lake – 4.7
Gaysville Bridge – 50.5
Stony Brook – 10.9
Tweed River – 42.2
Peavine Park – 64.9
Lion’s Club Park – Rochester – 50.8
Hancock Branch – 14.4

First Branch sites

First Branch Mouth -256.9*
Cilley Bridge – 142.9*
Chelsea Rec Park – 138.0*

Second Branch sites

Dugout Road – 188.2*
East Hill Road – 224.8*

Third Branch sites

Stock Farm Road – 161.4*
Golf Course Bridge – 122.5
Ayers Brook – 175.0*
Adam’s Brook – 14.6
Thresher Road – 40.7