Tracking Bacteria Pollution in the Lower Concord River

For the last 2 years, OARS program to monitor E.coli, a fecal indicator bacteria, showed higher than acceptable levels in the Concord River at the Roger's Street bridge in Lowell. This summer, we undertook a study to track down the source.

Six intrepid volunteers collected water samples from sites upstream of the bridge every Monday morning for 15 weeks. We analyzed the data, narrowed down the possibilities of where the bacteria could be coming from, and adjusted the sampling sites accordingly.

We determined that the source of the bacteria was probably River Meadow Brook, which comes into the Concord just above Roger's Street. It consistently had higher bacteria concentrations than the Concord sites. We then moved our focus to River Meadow Brook, trying to identify where the pollution was entering.

The bacteria levels were fairly consistent all the way to our most upstream sampling sites at Industrial Avenue, which averaged even higher bacteria levels than the downstream sites. This was surprising. It implied that the pollution was coming not from the urban center but from the more rural segments of the brook.

Our data also highlighted another potential source of pollution in the area where Newhall Street crosses River Meadow Brook. This location has ball fields and a popular playground with no access to the brook. The data showed that more than half of the time bacteria levels at the downstream site (RVM-001) were higher than at the upstream site (RVM-005), implying that there is a source in between. The Lowell Regional Wastewater Utility (LRWU) provided maps which show some storm sewer outfalls in this area. Further sampling will verify whether or not they are a significant source of bacterial pollution.

We would like to continue this study in the summer of 2021. With more focused sampling sites, we believe we will be able to pinpoint the source of the main bacterial pollution in River Meadow Brook, and then work to eliminate it.

This work was made possible through funding from the Greater Lowell Community Foundation.