The Connecticut River Conservancy has been collecting weekly water samples to test for E. coli bacteria in the Connecticut River and its tributaries. Some of the Hampden County sites in Massachusetts are heavily impacted by combined sewer overflows (CSOs), particularly from the more densely populated communities of Holyoke, Chicopee, and Springfield.

Reviewing five years of E. coli data collected from the Connecticut River shows that after dry weather, it is usually clean.

Results of Connecticut River Conservancy volunteer microplastics pilot monitoring program in the Connecticut River watershed.