The monitoring results for September have been added to our 2024 sampling season spreadsheet. All TRWA monitoring results may be accessed anytime from the Water Quality Monitoring Tab at the top of the TRWA website home page and clicking on either the sample bottle picture or link to the data under the Documents heading.
The results show high levels of nitrate downstream of the Brockton WWTP (Matfield River 1.66 mg/l and upper Taunton River at Cherry St. in Bridgewater 1.99 mg/l, over 4 times what we would like to see). This suggests that the Brockton WWTP plant may not have attained full operation of its nitrogen removal facilities. It also reflects very low available stream dilution (63 cubic feet per second (cfs) in September vs 193 cfs in August and 2,760 cfs in March). Since June when river flow fell below 400 cfs Matfield River nitrogen has been higher than we would like to see. We put the streamflow, the sampling date and flow trend at the top of the fourth page of our results spreadsheets because this and the flow record from the USGS Bridgewater gauge help us interpret our results. The other important results useful in interpreting our data are the water temperature measurements on our separate DO, pH and water temperature spreadsheet. Warmer water encourages bacteria criteria violations and algae growth.
Total phosphorus (TP) levels are good considering the low dilution indicating that the WWTPs with the major exception of Bridgewater WWTP did well with TP removal. The Town of Bridgewater was able to negotiate a schedule until 5/01/2027 for TP removal. In September TP in the Town River below the Bridgewater WWTP was 0.247 mg/l or 2.5 times what we would like to see to prevent algae blooms. Given the 4 million dollars spent to remove the Town River dam in order to restore fish passage to the upper river watershed and Lake Nippenicket, it is indeed unfortunate that the river will remain phosphorus polluted for 2 more years. Lack of rain for much of the sampling season means stormwater did not contribute major amounts of TP to the watershed’s rivers in September.
Lack of rain and stormwater runoff along with temperatures 4 to 6 C degrees cooler than August caused bacteria levels to be relatively low in September. The high value at Church Street, in Raynham about half way down the 40 mile Taunton River main stem is most likely from geese who have been observed sitting in the middle of the main channel feeding in the sediment because of the extremely low river flow.
In addition to our monitoring and USGS flow gauging, the other very important tool for evaluating Taunton River watershed health are the two MassDEP continuous monitoring buoys in Mount Hope Bay at the mouth of the Cole River (RI border) and in the central bay just south of the Braga Bridge, shown as gray teardrops on our Google map of monitoring locations on our website. If you click on either teardrop it says what they monitor continuously (every 15 minutes) at 1 meter depth from the surface and 0.5 meter from the bottom (DO, nitrate, chlorophyll-a, blue green algae and temperature). Because they monitor DO at depth rather than at the surface like we do these results are important for evaluation of the health of the bay.
In 2017 and 2018 and more recently in 2021 and 2022 these two sites recorded low DO for weeks at a time concurrent with high chlorophyll-a during the summer monitoring season. This long term low DO concurrent with high chlorophyll-a (algae) demonstrates the need for Taunton (almost done with construction finishing up now), Somerset (TN removal required by 6/01/2030) and Fall River (permit reissuance on hold) to remove nitrogen which causes the algae blooms which lower DO and impair the health of aquatic life. When this monitoring indicates that DO meets water quality standards SA 6.0 mg/l at the mouth of the Cole River and SB 5.0 mg/l south of the Braga Bridge concurrent with algae levels in a healthy range, chlorophyll-a 3-5 ug/l we will achieve water quality standards for Mount Hope Bay. As global warming causes ocean and Mount Hope Bay water temperature to rise it is important to lower nutrient levels (nitrogen and phosphorus) to meet DO levels needed for aquatic life.
Whether it is record warm water in the Gulf of Mexico supercharging hurricanes, droughts in the west and Canada creating epic fires, flooding and tornadoes in the south and midwest or New England weather changes consisting of warmer waters, higher tides, spring flooding followed by atypical dry or wet summers with more intense rainstorms when the do occur impacting stormwater Best Management Practice effectiveness. We need to plan for climate resilience. TRWA encourages you to come to our Regional Climate Change Impacts- Panel Discussion (9/28) at Bristol County Agricultural School (Bristol Aggie) in Berkley so you can question and hear from the experts. If you can’t make this program we will be having additional future programs on climate change and how to make our watershed more resilient to global warming.