On Friday evening April 26, twelve volunteers gathered at the canoe launch on the Assabet River in the southernmost corner of Acton. We were there to learn, or re-learn, how to sample and measure the quality of the water in the river, continuing the program of pollution monitoring begun more than thirty years ago by the Organization for the Assabet River, now known as OARS.
Our group of trainees included three newcomers and nine veterans. OARS’ water quality program is overseen by the Massachusetts Department of Environmental Protection, which requires that all community science volunteers be retrained every year on the exact procedures required to collect and document quality samples and accurate data, as spelled out in the “QAPP” (Quality Assurance Protection Plan.)
OARS’ water quality scientist, Ben Wetherill, first demonstrated how to capture samples of water in bottles, avoiding both the mud on the stream bottom and floating debris on the stream surface. Volunteers paired off and practiced bottle sampling, by either wading out into the river or using a long pole to reach out into the swiftly flowing center of the stream. Water samples are sent to a local lab to be analyzed for nitrate and phosphate concentration. These contaminants are nutrients that can stimulate excessive growth of aquatic plants, clogging waterways and degrading the river quality for both humans and fish. Wetherill recounted how OARS’ water quality data had been used in the 1990’s and 2000’s to make the case that municipal wastewater plants discharging into the Assabet River should be required to treat their effluent to remove phosphate. Following that change, phosphate levels in the river plummeted.
Next, Wetherill demonstrated how to lower an instrument package into the stream. The instrument measures the water’s temperature, dissolved oxygen content, pH and electrical conductivity. When explaining the logistics of water sampling, Wetherill said that on sampling days, volunteers should report to the OARS office at 6:00 to meet their sampling partner and get their equipment. A newcomer asked: 6:00 a.m. or p.m.? The answer was a.m.; water quality volunteers meet at 6:00 a.m. on Sunday mornings. The reason for this became apparent as Wetherill explained the dissolved oxygen component of the program. Dissolved oxygen rises during the day, as aquatic plants photosynthesize, and then falls throughout the night, reaching a minimum at sunrise. Sampling is timed to catch the near-minimum of the day, because that indicates the most stressful low-oxygen condition encountered by aquatic animals.
Acton resident and three-year OARS volunteer Kate Warwick explained why she does water quality monitoring: “It’s a way to give back. It takes so many man-hours to do this water quality volunteering, so it couldn’t be done without volunteers. We get to look at the data and see how things have changed over the years. The data can help us know what needs to be done to clean up the river.”
OARS’ program involves between twenty-five and 30 volunteers each year. In two- or three-person teams, they visit 25 sites each month from March through November, spanning the Assabet, Sudbury and Concord Rivers and their tributaries. There are two sites in Acton: the canoe launch and a site on Nashoba Brook near Wheeler Lane. The Town of Acton contributes funding in support of the water quality program.
Michal Mueller is a 20-year veteran of OARS water quality monitoring. As a middle school science teacher, she said: “I wanted to be able to tell my students, ‘You can do things to make the world better.’ There are so many big bad things going on in the world, but this is something that I can do to help. It was like a miracle when they got the wastewater treatment plants to reduce their phosphate. And getting out there early on Sunday mornings and seeing the progression through the seasons. It’s soothing and inspiring to be out there when everything is just waking up. It uplifts my spirits.” As Michal and I chatted, the other volunteers packed up and left, and dusk fell. And then, a beaver swam by.
Results from OARS’ water quality monitoring program, going all the way back to 1992, can be found on their website. It’s too late to train for the 2024 water quality monitoring season, but there is always next year, and OARS offers other ways to volunteer, including water chestnut removal, river clean up, and helping with events; visit their Volunteer website.
Kim Kastens is a writer, editor and board member for the Acton Exchange. She has been an OARS water quality volunteer since 2016.