A Rainy Summer on the Westport River

This summer’s water quality results show just how strongly rainfall can influence conditions in the Westport River. Several significant rain events occurred immediately before our Wednesday sampling, including more than 3.6 inches in the week before June 24, 3 inches in the 48 hours before July 8, and 2 inches in the 24 hours before July 22. These storms produced some of the highest fecal coliform readings of the season, with elevated levels recorded across multiple monitoring sites. The June 24 sampling round was particularly notable, with elevated bacteria at all seven monitoring stations, while the July 22 event produced another widespread increase. Smaller spikes followed additional rainfall in late July, early August, and early September. Overall, about 30% of individual samples exceeded the Massachusetts recreational standard of 200 colonies/100 mL, but the data show that most of these exceedances were concentrated around a handful of wet-weather events rather than occurring consistently throughout the summer. During drier periods, bacteria levels dropped sharply, with most stations returning to relatively low readings.

Compared with the past two summers, 2026 had more frequent and pronounced bacteria spikes, reflecting the unusually wet conditions and, importantly, the timing of rainfall just before sampling. These year-to-year differences highlight why our long-term monitoring is so valuable: a single high reading tells us very little by itself, while patterns across many years help us understand how rainfall, runoff, tides, and watershed conditions influence water quality. We are especially grateful to the volunteer citizen scientists who help make this monitoring possible. Their time, careful attention to sampling protocols, and commitment throughout the summer are an essential part of WRWA’s water quality program.