The TRWA water quality monitoring results for April are available. The results may be found on our website here and at the Water Quality Monitoring Tab by clicking on the sample bottles picture or the link further down the page under Documents.
As evident in the nightly news, global warming is affecting the world’s weather. In the western United States, we see drought and wildfires. In the Gulf states, we see rapidly intensifying hurricanes due to the warmth of Gulf waters. We are seeing an unprecedented number of tornadoes and floods in the south and mid-section of the country. Warm air holds much more moisture than cool air, so when the warm air picks up moisture from warmer than historical ocean waters it carries a lot of moisture with it until it encounters cooler air coming down from the north, setting up a battle of the air masses along a front. This results in violent weather, tornadoes and flooding like we have recently seen along the Mississippi River.
In New England, Massachusetts and the Taunton watershed, global warming has changed our weather pattern as well, however, not as dramatically as many other parts of the country. Our new weather pattern has more intense but relatively short duration rainstorms in winter through early spring, followed by hot summers and drought punctuated by very short duration intense rainstorms. Short duration summer rainstorms give the rivers in the watershed a dose of polluted stormwater runoff (which we measure as high bacteria with spikes in phosphorus and nitrogen). These summer short intense rainstorms are not sufficient to restore the groundwater level needed to supply summer river flow between storms, resulting in low river flow.
TRWA’s sampling team is measuring how these changes affect the water quality of the rivers in our watershed each month. The information collected underscores the need for action to mitigate the impacts of our new climate and river flow regime. These measures include conserving water and encouraging rainwater to go back into the ground rather than running off quickly.
In April, we sampled shortly after a small rainstorm, so river flow measured at the USGS Gage in Bridgewater was moderately high at 675 cubic feet per second (cfs). The results for total nitrogen downstream of the Brockton WWTP were higher than we would like to see, however their total nitrogen effluent limitation is seasonal from May 1 to October 31, so this is not unexpected. The total phosphorus levels measured looked ok. Bacteria (enterococci) had a significant number of state water quality criteria exceedances, likely due to urban stormwater runoff.