July 2020 Water Quality Report

Lack of rainfall leads to reduced stormwater pollution and low water levels. 

Over 50 volunteers contributed to the success of July’s Citizen Water Monitoring Network (CWMN) mission. The data collected helps NepRWA better understand where and how we can reduce pollution to the Neponset River and its tributaries 

E. coli Results

E. coli is a bacteria that often indicates contamination from human and animal waste.  The bacteria associated with this waste can make people sick. 

In July, 68% of samples met the EPA swimming standards and 90% met the EPA boating standards. This is a slight improvement from the E.coli levels during the June sampling. Typically, E. coli levels climb throughout the summer as temperatures increase however this year’s dry conditions may be keeping E. coli levels from spiking. Lack of precipitation means less stormwater runoff and less washing of dog waste and organic debris into the river. The drought also results in lower groundwater levels which may reduce seepage from leaky septic and sewer pipes. However, many areas of the Neponset, continue to have unhealthy E. coli levels. Notable high levels were recorded along Hawes Brook and Unquity Brook. 

Residents can help reduce the amount of E.coli bacteria in the water by always picking up after your dog and throwing the waste in a trash can — and by making sure that your septic system is working properly. The E. coli results are summarized in the map and graph below. 



Phosphorus Results 

Phosphorus is a key nutrient for plants and is a large component of most fertilizers. Unfortunately, when fertilizer washes off lawns it can end up in streams and ponds. Too much phosphorus can lead to harmful algal blooms, cyanobacteria blooms and fish kills. In July, 39 of the 40 sites tested had unhealthy levels of Phosphorus! Phosphorous pollution is a HUGE issue for the Neponset with many areas having Phosphorus concentrations 2 to 3 times the healthy level. For tips on how to reduce your phosphorus impact on the river visit https://yourcleanwater.org/lawn/.  


Dissolved Oxygen Results 

Dissolved Oxygen has been referred to as the “air” fish breath underwater. If the concentrations of oxygen in the water get too low fish and other aquatic organisms can not survive. Low dissolved oxygen is often the result of too much decomposition of algae caused by excess nutrients in the water body. 83% of the sites sampled had water with healthy levels of dissolved oxygen. This is good news for most fish and aquatic insects. However, fish living in Pine Tree Brook and the most upstream reaches the Neponset face low oxygen levels and will not be able to survive without moving to another part of the watershed. The results are summarized in the map and graph below. 



Follow this link to a list of CWMN site descriptions.

Thank you to all the dedicated volunteers who make up the backbone of the CWMN program! If you have any questions about the CWMN results, please contact Environmental Fellow, Declan Devine at devine@neponset.org 


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