June 7, 2011: Tests find rivers in good condition
The first round of annual testing of local rivers for bacteria by volunteers found that the Merrimack River remains extremely clean, as it has been for years, while the Souhegan River showed some problems around Amherst and Milford, but was generally in good shape.
This is the 15th summer that volunteers with the Souhegan Watershed Association and the Lower Merrimack River Advisory Council have taken samples at two dozen locations every two weeks. The samples are tested at local wastewater treatment plants for E. coli bacteria and dissolved oxygen, providing a measure of the rivers’ cleanliness and health.
Almost all of the bacteria readings from the first sampling on June 7 found fewer than 88 colonies of bacteria per 100 milliliters of water, meaning they were safe for swimming under state standards. A few in Milford, from near the Boys & Girls Club of Souhegan Valley through the Boston Post Road canoe port, had higher readings that indicate swimming is frowned on.
Such readings aren’t unusual in the middle stretch of the Souhegan, where the river slows down as it transitions from the rapids-filled upper river to the more placid lower stretch.
E. coli bacteria in the Souhegan can be a sign of contamination caused by runoff, from sewage or runoff of fertilizer and other materials, often caused by rain. The June 7 testing followed several clear days, so runoff should have been limited.
Volunteers are still needed to collect samples at some locations. Those interested should e-mail Karen Mattor at email@example.com.
– DAVID BROOKS