Conducted between April and November each year -- and shared with the public online as well as with local boards of health and the state -- the PRCWA report helps identify areas where pollutants and other issues within the watershed are occurring. Each month water samples from various spots are tested for levels of acidity, nitrogen and phosphorus, dissolved oxygen, and e.coli. The source is also analyzed to measure the water’s turbidity, temperature, depth, and velocity.
In the latest report, samples taken from the Mill River near Elm Street tested higher than normal for phosphates every month and for nitrates during 5 out of the 8-month testing period. High levels of nitrates were also found in samples taken from Ox Pasture Brook in Rowley during three months. Increases in these nutrients overstimulate the growth of algae, which floats to the water surface, blocking out sunlight and eventually killing the plant life below. Since the decaying plants needs oxygen in order to decompose, the amount of oxygen being used in this area is far greater than the amount being produced. Low levels of dissolved oxygen in the water are indicators of a potentially significant decrease to the health and viability of aquatic life. Failing septic systems or treatment plants and run off from fertilized lawns and agricultural fields are often the culprit when high levels of nitrates and phosphates are identified.
Evidence of e.coli colonies in greater than typical quantities appeared in 6 of the monthly water samples taken at Ox Pasture Brook --including a reading of “too numerous to count” in November 2012. Officials believe an overabundance of geese on two ponds located just above the testing site could be a factor.
Several sites along Penn Brook and a section of Parker River in Georgetown all showed high level of the bacteria in November. There were four instances of raised e.coli levels in samples taken from Little River during the testing period and one from Mill River taken last July.