October was the last sampling month of the TRWA 2025 sampling season. I want to thank our volunteers for a very successful season where not a single sample was missed! I hope our samplers are able to attend TRWA’s annual meeting on Saturday, November 1st at Bristol Aggie, 4:00 to 6:30 PM so we can recognize your great work!
In October we caught a large rainstorm. As shown on the Bridgewater USGS River Flow Gage, two days before we sampled river flow was only 81 cubic feet per second (cfs). The storm on 10/13 which lasted into the morning we sampled (10/14) brought river flow up to 743 cfs when we sampled.
The storm brought higher dilution of wastewater treatment plant effluent resulting in lower nitrogen levels. Stormwater pollution raised total phosphorus levels and very dramatically increased bacteria (enterococci) levels at all sampling locations.
The biggest water quality problem in our watershed is bacteria levels with almost all monitoring stations exceeding the enterococci water quality criterion of 35 colony forming units (CFU) by large amounts after rainstorms. This is a result of lack of stormwater treatment by green infrastructure such as infiltration basins, infiltration trenches, rain gardens, tree filters, etc. in the watershed. Stormwater infiltration even if there is only physical space for an undersized unit that captures and treats the first flush is effective for bacteria and phosphorus control. In addition, a significant increase in watershed stormwater infiltration is needed to address the low groundwater, water supply and stream flow issues we see every summer as a result of global warming.
Because of TRWA documented water quality standards violations caused by stormwater throughout the Taunton River watershed, TRWA believes EPA should use its “residual designation authority” to regulate large non-regulated commercial stormwater sources in our watershed. The Clean Water Act (CWA) recognizes that other stormwater sources may need to be regulated on a case-by-case or category-by-category basis based on additional information or localized conditions. The authority to regulate other sources based on the localized adverse impact of stormwater on water quality through CWA permits is commonly referred to as the “Residual Designation” authority.
We are always looking for new water quality sampling volunteers. Training for new volunteers and refresher training for current volunteers is 9:30 AM the last Saturday morning in March 2026 at our Sweets Knoll Watershed Center. Sampling is done by nine teams of samplers on the second Tuesday morning of each month from April through October.