October Nitrate, Total Phosphorus and Enterococci Bacteria Results

The October nitrate, total phosphorus, and enterococci results are back from our contract lab and have also been added to the website monitoring data page. These are the last results for the 2019 monitoring season which runs from April through October so we can look at not only the month of October but the year as a whole.

The October results for 2019 are a little worse than October 2018 but looking at the May to October averages for both years they are very similar. Both 2018 and 2019 were relatively similar, wet years providing high wastewater treatment plant (WWTP) dilution. Results for nitrate our most critical water quality parameter because of the impact of excess nitrogen on the ecology of the estuarine portion of the river and Mount Hope Bay look better in 2019 and 2018 (two recent wet years) than 2017 and 2016 (two dry, low river flow years) because of the higher river flow dilution.

We see the highest levels in the upper watershed (locations MAT-01, TWH-01, and CHE-01) reflecting the fact that Brockton and Bridgewater have not completed required upgrades to remove nitrogen yet. Brockton and Bridgewater are scheduled to remove nitrogen in April and May of 2022 respectively. Despite looking better than the more typical dryer summers of 2016 and 2017 the nitrogen levels in the upper watershed were still 3 to 4 times what they should be and levels in the lower river were approximately 1.5 times the EPA and MassDEP water quality criteria targets established for the Taunton River.

A good news story is that the Nemasket River had low nitrate levels all year reflecting the completion of the upgrade of the Middleboro wastewater treatment plant early last year. The Mansfield/Norton/Foxboro nitrogen removal upgrade is scheduled to go on line in early 2020 which should help the Three Mile River.

The most critical upgrades we are looking forward to in order to lower nitrogen levels throughout the river are Taunton, Brockton, and Bridgewater which are required to remove nitrogen by 2022. We are hoping EPA and MassDEP will assure Taunton, Brockton, and Bridgewater comply with their permit schedules to complete their upgrades by 2022 and resume Clean Water Act permitting in the Taunton River watershed by issuing the remaining two major permits Somerset and Fall River with WWTP upgrade schedules.

As mentioned last month we are carefully watching the new enterococci bacteria testing results. As we accumulate more data on this parameter, we will get a better idea of seasonal fluctuations and potential sources.

In a final piece of monitoring news TRWA received MassDEP approval of its Quality Assurance Project Plan (QAPP) on October 2, 2019. TRWA is one of the few citizens volunteer monitoring programs with an approved QAPP which means the Commonwealth can use our data in development of the biennial 303(d) list of Impaired Waters developed by all states every even year pursuant to the Clean Water Act.

We appreciate the hard work and dedication of our volunteers and the support of our TRWA members and donors who make this effort possible!

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