Understanding How Rivers Carry Nutrients Through the Watershed

Lilia Bartolotta walks with purpose. Slowly, as she breaks through a crunchy top layer and sinks into the snow, but with purpose. The sun is out and some birds are chirping above, but it is certainly cold early this February morning, hovering around freezing.

She’s out to do her river monitoring work, which will allow the Buzzards Bay Coalition to track sources of pollution flowing into our coastal river network, as well as changes in river water level. All are

important metrics to understanding what’s happening within the Buzzards Bay watershed.

This outing has required Bartolotta to put on tall muck boots, as many riverbanks from which she samples water are covered in more than a foot of snow. While in past years, any accumulated snow may have melted before she did her rounds in February; this year, snowbanks pose a little challenge.

One of Bartolotta’s important responsibilities as a Buzzards Bay Coalition Bay Science research assistant is the river monitoring she conducts at 13 locations across the watershed. She travels to her select destinations throughout the year, through snow, rain, and summer heat.

These freshwater sites were chosen because their data elicits how the variety of inputs (i.e. streams, brooks, and rivers) transport pollutants, namely nitrogen, through the watershed and into our monitored embayments. “We have a diverse set of landscapes, from cranberry bogs in the east of the watershed to urban centers to more field-based agriculture in the west,” says Rachel Jakuba, Vice President of Bay Science. “Rivers are major water and nutrient conduits to Buzzards Bay.”

At each site, an app on Bartolotta’s phone downloads data from a sensor that continuously logs water level and temperature at the site. She also does a spot check of the water level by comparing readings with a manual gage, and a temp check with a handheld thermometer.

Water level can be used to calculate yearly patterns in river flow. In the springtime, with high precipitation and (this year especially) a melting snowpack, it is safe to assume that flows will be stronger than they will be in the summer. But from year to year and station to station, how does that flow change? And how does the flow affect how much nitrogen flows to downstream embayments, where the effects are more apparent in murky water, algal blooms, and loss of eel grass?

When she arrives at Angeline Brook, Bartolotta comments that at 35 cm, it is the highest she has ever seen it.

Next, she starts collecting water in bottles bound for study at Woodwell Climate Research Center, the organization that started river monitoring in Southeast Massachusetts and the Cape and still analyzes the water that is collected. It’s fun to watch. She’ll either pull up a bucket from a bridge above the river or wade into the water itself.

Buzzards Bay Coalition board member and Woodwell senior scientist Christopher Neill devised this particular monitoring program with the Coalition and Casey Kennedy at the UMass Cranberry Station in Wareham. Last year, the Buzzards Bay Coalition became lead organization for the river monitoring program and Bartolotta took over the sample collection.

Bartolotta enjoys crunching data when she is not out in the field, but revels in the opportunity to be out in nature, be it snow, rain, or heat. “I saw a bald eagle above me when I was out on the Westport River,” she says. “I like to be out among the rich mosaic of plants and fungi. There is one species with long, translucent stalks that blooms for only a few days each year.”

She loves when her river monitoring efforts afford her the opportunity to bear witness to such a unique event.

But it is the data she is collecting that will reveal the most about the hydrological dynamics of our unique watershed and document the nitrogen pollution from septic systems, fertilizers, and runoff from roads as it moves from the watershed to rivers that flow into the Bay. Studying how much nitrogen is flowing out of the rivers at different times of year gives us a clearer picture of what’s going on in the Bay.