Water Quality Monitoring Program

To gauge the health of our waterways, a dedicated crew of volunteers performs monthly testing at 20 sites (see “documents” below for the sites) on the Taunton River and tributaries, measuring levels of nitrate, total phosphorus, bacteria (fecal coliform in the past and enterococci bacteria starting in  2019), dissolved oxygen, pH and temperature (click on the picture of the sample bottles or the first link listed below to see the 2016, 2017, 2018, 2019, 2021, 2022 and 2023 data – sampling was suspended in 2020).

The TRWA has been testing some of these sites for over 28 years, digital copies of our data back to 2003 are available. This citizen collected data helps form a picture of the watershed’s health and keeps the spot light on areas and actions needed for further improvement. Our citizen monitors and photography volunteers also take periodic pictures (click on the picture of the green algae bloom below to see some pictures).

The primary water quality problems in the Taunton River watershed are driven by excess nutrients (nitrogen and phosphorus), droughts, and floods. Global warming causing more extreme weather (more severe hot summer droughts and larger winter/spring floods along with sea level rise) and rapid development disrupting hydraulic cycles (loss of groundwater recharge and stream base flow) exacerbates our water quality problems. Nutrient pollution causes algae to grow and fish & native vegetation to die.

Working to make the watershed more resilient and improve water quality are the actions by the watershed’s municipalities to upgrade treatment to remove nitrogen and phosphorus (click here to see schedules) as well as efforts to implement stormwater management techniques to soak up the rain (preserve and restore predevelopment hydrologic conditions, smart development and stream buffer protection). Better nutrient control will decrease nuisance rooted aquatic plant and algae proliferation improving aquatic life diversity throughout the watershed. As discussed below better nitrogen control is needed to address low dissolved oxygen and algae blooms measured by MassDEP’s continuous monitoring buoys at the mouths of the Taunton and Cole Rivers. The new stormwater permit issued by EPA and MassDEP became effective on July 1, 2018. The permit will facilitate efforts to restore groundwater and streamflow integrity. Improved stormwater management will improve the rivers flow regime and reduce pollution (including nutrient loading) from this source as well as mitigate some of the adverse environmental impact of development. The new EPA stormwater permit will help but falls short by not addressing stormwater pollution from existing development. Region 1 of EPA should use its residual designation authority to require general permit coverage for all privately owned development with an impervious surface area of 1 acre or more as it did in the Long Creek watershed in Maine.

Program Overview

TRWA monitors the main stem of the Taunton River at five locations Berkley to Bridgewater along with critical tributaries feeding the river at fifteen additional locations during the early morning hours the second Tuesday of each month April to October. The reason we do this is to provide the watershed a regular check-up essential to continue the focus on correction of previously identified problems and to identify new issues.

Nutrient Growth Low Flow/No Flow Photo Documentation
Water Quality Monitoring DataCurrently the biggest TRWA monitored problem pollutant in the watershed is excess nitrogen loading by wastewater treatment plants (66% of load) and other sources including stormwater runoff, excess lawn/turf/crop fertilization (and sloppy application of fertilizer i.e. on sidewalks, roads and driveways), pet wastes, stream bank erosion, stream buffer loss, and poor manure management from farming areas (34% of load). A comprehensive state sponsored 2004 to 2006 study throughout the Taunton River Estuary and Mount Hope Bay SMAST, Summary of Water Quality Monitoring Program for the Mount Hope Bay Embayment System (2004 – 2006) (August 16, 2007) documented high algae and depressed dissolved oxygen attributed to high nitrogen loads. TRWA monitoring continues to measure nitrate (a portion of total nitrogen) in the main stem of the river at levels 2 to over 4 times the in-stream target total nitrogen level 0.45 milligrams/liter (mg/l) MassDEP, EPA and RI say is needed to protect the estuary (total nitrogen = nitrate + organic nitrogen + ammonia + nitrite; so despite the fact we measure only one component of total nitrogen (nitrate) the levels measured are much too high). Our monitoring indicates that action to remove nitrogen from wastewater treatment plants is necessary. As the plants are upgraded to remove nitrogen (a requirement of new discharge permits) our monitoring is important to track progress as nitrogen levels (and water quality) improves and to identify sources other than treatment plants in need of remediation.

The next most critical parameter we measure is total phosphorus important in the upper fresh waters of the watershed (main stem upstream of Raynham) and the tributary freshwater rivers/streams/lakes/ponds. Just as nitrogen is the limiting nutrient in the estuarine portion of the watershed, phosphorus is the algae growth limiting nutrient in the freshwaters upstream. Monitoring has measured total phosphorus levels near the riverine target of 0.10 mg/l (0.05 mg/l is the target for lakes/ponds/impoundments) at a number of locations along with criteria exceedance on tributaries such as the Town and Three Mile Rivers. The treatment plants generally have total phosphorus limits which are being adjusted upon renewal as needed. Phosphorus is an important pollutant in stormwater but since it attaches itself to particulates it can be filtered out by soil infiltration Best Management Practices (BMPs). Phosphorus is less mobile than nitrogen which can pass through soils and travel with groundwater. Total phosphorus in stormwater can be effectively removed by infiltration of first flush flows. Caution is needed in assessing in-stream total phosphorus levels because during blooms (present in our watershed for much of the summer) algae can use up total phosphorus so quickly measurement of in-stream total phosphorus alone can give artificially low values. For this reason TRWA in 2016 added photographic monitoring to document the widespread algae blooms and excess rooted aquatic plant growth in the upper watershed to supplement its chemical monitoring (click on the first picture (of the green algae bloom) above to view some photos).

The third most critical parameter we measure is bacteria level. Fecal coliform bacteria levels in excess of 400 colonies/100 milliliters indicates the potential presence of disease-causing organisms (usually gastro-intestinal) for swimmers or kayakers. The three sites on the Mill River in Taunton and the Town River in Bridgewater have occasionally had elevated levels in the 500 to 2000 colonies range. Improvements in sewer system integrity and treatment plant and pump station capacity have resulted in much improvement in recent years. For the most part fecal bacteria levels are now fairly good. Our monitoring helps assure the locations we monitor are safe for recreation. In 2019 TRWA changed its bacteria analysis to monitor enterococci bacteria a newer indicator to be consistent with the updated state water quality standards. Enterococci bacteria levels in excess of 61 colonies/100 milliliters as a single sample maximum (SSM) and 33 colonies/100 ml as a geometric mean of the last six months of samples violate the new state water quality criteria. In 2019 our first year using the new indicator we saw frequent criteria violations of the new standard. Results since that time have been mixed. More monitoring with this new more sensitive bacteria indicator is needed to pin down sources and their significance.

Over the last several years other parameters tested (dissolved oxygen (DO), total suspended solids (TSS), pH and temperature) have not exhibited unusual levels and/or water quality criteria violations observable by monthly grab surface sampling collected from the free-flowing main stem of the Taunton River and the main flow from its tributaries in the upper watershed where TRWA samples. Low dissolved oxygen levels which do not meet water quality criteria were measured by MassDEP during the summer of 2017 for weeks at a time at their continuous monitoring buoys in upper Mount Hope Bay at the mouths of both the Taunton and Cole Rivers (see TRWA Google map for buoy locations). Low DO was observed following events where chlorophyll-a peaks of 25 to 100 ug/l were observed, which demonstrates that the low DO resulted from algae blooms (eutrophication) caused by excessive nutrients which the treatment plant upgrades and improvements in stormwater management are designed to partially correct.

Nitrogen induced eutrophication in the estuary threatens the endangered Atlantic sturgeon, Winter Flounder, Sea Run Brook Trout and the ability of the Taunton watershed and Mount Hope Bay to support the thriving balanced indigenous population of fish, aquatic life and wildlife we all want to see throughout the watershed. This is why TRWA’s advocacy efforts to convince EPA to reissue the two remaining overdue permits in the watershed Somerset and Fall Fiver is so important.


Link to TRWA Monitoring Results Data Page (on TRWA Website)

Volunteer Monitoring Program Forms and Information:

Information on Taunton River Watershed Municipal Wastewater Treatment Plants (WWTPs) (PDF)

Important Quotes from First Circuit Court of Appeals Concerning Losing Nutrient Limit Permit Appeals

2018 Taunton River Watershed Monitoring Results Narrative Summary (PDF)

2017 Taunton River Watershed Monitoring Results Narrative Summary (PDF)

2017 Taunton River Watershed Report Card (PDF)

2016 Taunton River Watershed Monitoring Results Narrative Summary (PDF)

2016 Taunton River Report Card (PDF)

2016 to 2014 Taunton River Water Quality Report Cards (PDF)

2015 Taunton River Watershed Monitoring Results Narrative Summary (PDF)

2017 Bridgewater Compliance Schedule Order (PDF)

Taunton River Watershed CWA Permit Nutrient Compliance Schedules (PDF)

Taunton River Watershed Clean Water Act (CWA) Permit Re-issuance Status and Nitrogen Limits (PDF)

MassDEP Letter of 11-13-2018 Not Supporting DO Criteria Revision (PDF)

MassDEP Letter of 7-29-2019 Not Supporting Taunton’s Claim That DO Criteria Have Been Attained (PDF)

TRWA Comments on Taunton WWTP Final Environmental Impact Report (FEIR) (PDF)

Monitoring Program Brief Summary (PDF)

Most Common Sources of Environmental Impairment in Massachusetts (PDF)

Stormwater Fact Sheet (PDF)

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