Souhegan River Tests High for E. Coli in Amherst

Submitted by George May, Souhegan Watershed Association

High E. coli counts were recorded on the Souhegan River between Wilton and Amherst for no apparent reason, according to the water testing program carried out by the Souhegan Watershed Association. There was a little rain the day before samples were taken but not enough to wash bacteria into the river. Heavy rains do raise the bacteria counts. Warm weather and low flow probably accounts for the higher bacteria levels according to the program.

Very clean results were found in the upper watershed, but the counts jumped at downtown Wilton. They held in the 200-300 range through Milford and Amherst and began dropping by the time the river reached the Amherst Canoeport at Boston Post Road near Souhegan High School. The river cleaned up again as it passed through Merrimack to its discharge into the Merrimack River.

The program uses readings of 88 or less to indicate water clean enough for swimming with an upper acceptable limit of 126. Readings higher than this can cause gastrointestinal problems if swimmers ingest any of the water and eye and ear infections through contact. Readings over 400 are dangerous. The highest reading, 727, was seen near the Souhegan Valley Boys and Girls Club inMilford. The river jumped up to 517 at the Amherst conservation land site across from the Amherst Country Club but this may be partly attributed to the influence of Town Brook that runs through the center of Amherst. 

There were no other readings over 400. All of the results, as well as results for the entire summer, can be seen on this map. 

None of the usual swimming holes along the river had readings higher than 88 and would be considered clean.

The Merrimack River between Manchester and Tyngsborough was another story. The river in this stretch was basically clean. There was one reading of 131 taken just upstream of the confluence with the Souhegan, but this was taken in an eddy and may not reflect the river as a whole. The upper stretch of the river was tested, but the results were not available at this time; these results will be posted on the website map when available. 

There will be one more test date this season. All of the 30 plus sites are manned by trained volunteers and all of the biological and chemical tests are done in certified labs in Manchester, Nashua, Merrimack, and Milford. This is the 17th year of continuous testing by the watershed association. There will be some additional testing done through two electronic monitors in each of the two rivers that will remain in the rivers and collect data throughout the year.

Here are the results for all of the sites tested:

E-COLI MONITORING RESULTS FOR TESTS TAKEN ON AUGUST 27, 2013

SOUHEGAN RIVER SITES:

1. Billy Ward Pond, Ashburnham  #1 – 2.0, #2 – 2.0