The monitoring results for October are available on our monitoring results tracking spreadsheet. The monitoring results have also been added to our website 2024 sampling season spreadsheet. The 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. These are the last monthly results of the 2024 (April through October) sampling season.
The results again show high levels of nitrate downstream of the Brockton WWTP (Matfield River 0.79 mg/l and upper Taunton River at Cherry St. in Bridgewater 0.79 mg/l, double what we would like to see but half of last month so an improvement). This illustrates the importance of river water dilution as shown on page 4 of our spreadsheet. Stream flow measured by the USGS gauge in October was double what it was in September so nitrate concentration was reduced by half by this higher river flow. 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 were fairly good considering the relatively low dilution indicating that the WWTPs did well with TP removal. Even Bridgewater, which has not achieved final TP limitations, did well enough for the Town River to meet criteria. As mentioned last month, lack of rain for much of the sampling season means stormwater did not contribute major amounts of TP to the watershed’s rivers most of the time in September and October.
General lack of rain and stormwater runoff along with temperatures lower than summer caused bacteria levels to be relatively low in October. The higher values we detected are likely from a short rain event that occured the evening before we sampled.
As mentioned last month, global warming is changing the planet’s weather. We see record warm water in the Gulf of Mexico supercharging hurricanes, droughts in the west and Canada creating epic fires, widespread flooding and tornadoes in the south and midwest. For us in New England we see spring flooding followed by atypical dry or wet summers with short duration more intense rainstorms when they do occur impacting stormwater Best Management Practice effectiveness. We need to plan and implement actions for climate resilience. TRWA’s volunteer monitoring program is helping inform what we need to do.