Our Program

MRWC collects water quality data at sites along the main stem of the Merrimack River, from Manchester, NH to Newburyport and Salisbury, MA. MRWC staff and water quality monitoring volunteers collect data on fecal indicator bacteria concentrations as well as physical and chemical parameters in the river: pH, salinity, total dissolved solids, conductivity, temperature.

The term “fecal indicator bacteria” (FIB) refers to bacteria that “indicate” the presence of feces in the water.  We measure two FIB in our program–Escherichia coli (or E. Coli.) and Enterococcus. Both of these bacteria are found in the intestines of warm-blooded animals (including humans and dogs). While neither FIB cause disease themselves, their presence suggests the water may be contaminated with feces and other disease-causing organisms  like viruses and protozoa.

Why is this important?

We have found high concentrations of FIB at times in the Merrimack, suggesting fecal contamination levels that make recreational activities, such as swimming or boating, potentially unsafe. However, we know that conditions in the Merrimack are not unsafe all the time.

FIB are useful for monitoring programs because they can help us understand if the river is safe for recreation or not. Elevated concentrations of FIB in waterbodies polluted by human sewage are correlated with increased gastrointestinal illness among swimmers. Even though the FIB specifically don’t make people sick, this correlation means state and federal authorities can develop water quality guidelines based on FIB concentrations. We use those guidelines in our program to categorize the bacteria concentrations we measure as “safe” or “unsafe” for recreation.

In the Merrimack, there is still a major gap in understanding exactly when, where, and for how long the river is unsafe to use after large contributions of fecal contamination to the river. The river monitoring program at MRWC aims to fill in that gap in understanding. By collecting data consistently and continuously, we can better understand how changing environmental conditions and increasing human impacts affect the water quality of the Merrimack River. We can then use these data to advocate for the right solutions to make improvements.

Funding for water quality monitoring is provided by Massachusetts Bays National Estuary Partnership, under EPA grant number 00A01085-0.

Photo: MRWC

Photo: Kate Delaney

Photo: MRWC