The headwaters of the Marstons Mills River contain approximately 150 acres of cranberry bogs. We have been collecting water quality data at the bogs that shows more than 8,000 kgs of nitrogen flows out from them into the Three Bays Watershed each year. The bogs contain wetlands and on old maps, the entire site was marked “ponds and wetlands”. This is a collection area for the groundwater from much of the surrounding residential developments.  Interestingly, the farmers tell us that while they used to apply fertilizer, little is now needed since the crop do well without needing additional nitrogen fertilizer.

This makes sense when we examine the results of our monitoring.  Approximately 40% of the watershed’s excess nitrogen load flows through the bogs and into the Marstons Mills River.

Our new understanding is that the bogs could play a vital role in reducing this same nitrogen load in our watershed. We are working closely with the farmers to examine a series of pilot programs that would allow for significant nitrogen attenuation to occur without negatively impacting their farming of the bogs. Wood chip-based bioreactors are just one of the half dozen pilot projects we are planning to install and test in these bogs.

The University of Massachusetts School for Marine Science and Technology (SMAST) is out weekly at seven sites in the bogs collecting water samples for total nitrogen and phosphorous analysis and taking measurements including dissolved oxygen and temperature.