Our volunteers have been hard at work collecting water samples around the watershed, and we just got the results back from the laboratory for our August sampling date.
This map shows the bacteria data collected from the Citizen’s Water Monitoring Network (CWMN) sampling event that took place on August 28, 2014. From this data we can see that almost half of our sampling sites (19 out of 41) exceeded the state E. coli standard of 235 MPN/100mL. These sites are indicated on the map by the orange and red dots. The six large red dots represent the areas where the E. coli levels greatly exceeded the state standard ranging anywhere from 1020-2010 MPN/100mL. Site PUB022 located on Purgatory Brook in Westwood was the location of the highest level of bacteria, with 2010 MPN/100mL.
The month of August was particularly dry with a total rainfall of only 1.3 inches. The average rainfall for the month of August during the past 10 years is 4.5 inches. There were two sites that could not be sampled due to low water levels from the lack of rain. Those sites were PQB036 on Pequit Brook in Canton and site UNB002 on Unquity Brook located in Milton. There were also other areas within the watershed where several volunteers noted that it was difficult to take samples because of low water levels. We need rain to help keep our streams and rivers flowing, and replenish our groundwater supplies that many rely on for drinking water.
The bacteria levels for August were lower than those earlier this year, partly due to the dry weather on sampling day. When there is a lot of rain, there is also a lot of runoff from roads and parking lots that carry bacteria and other contamination into our river and its tributaries.
NepRWA is working to help towns in our watershed address polluted runoff through the Neponset Valley Stormwater Collaborative and other projects. You can read more about the Collaborative here.
If you have any questions about the data, or want to become a CWMN Volunteer, please contact Environmental Engineer Sarah Bounty at 781-575-0354 x302 or bounty@neponset.org.
October 2014
Erin Siulinski, Fall Intern
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