ATHOL – On Sunday, volunteers did biomonitoring at the newly-daylighted Mill Brook, after it has run unseen beneath the parking lot at the former Lord Pond Plaza for six decades.
Ivan Ussach, director of the Millers River Watershed Council, said interest in monitoring the stream was piqued after there were reports of wildlife returning to Mill Brook. Work was done over several years at a cost of $3 million to transform the parking lot from six acres of moisture-impervious, heat-reflecting blacktop into a greener, climate-resilient location. A ribbon cutting was held in September.
“The wildlife returned to the stream very soon after the daylighting, so we thought it would be good to see if the benthic (bottom-dwelling) macroinvertebrate population was part of that section of wildlife that was returning,” he said. “The presence of these bugs is a good indicator of water quality.
“But because the stream has just been daylighted, it presents a novel opportunity to see…what the benthic bug population looks like,” Ussach added.
Ussach explained that benthic macroinvertebrates “reside in the benthic layer, which is the sediment. Macroinvertebrate just means it has a vertebrae and is large enough to see. Basically, they are the larval stage of many species of flies, mayflies and others….When you find these sensitive types in the water, it means the water is in good shape. And there other species which are more tolerant of pollutants, and if you find a lot of them it suggests the water is more contaminated. This is our first look at Mill Brook.”
Asked about the difficulty in identifying creatures that may be mere millimeters long, aquatic biologist Cathy Szal said, “Sometimes you need a microscope to do a decent job, but a lot of the things we’re looking at today, we can tell by looking at them. We often can’t call the species, but we can call the genus just by looking at them.”
Assisted by Bethany Nichols of the Worcester Conservation District, a rubber-booted Szal stood in Mill Brook and flipped rocks, dug through sediment and collected samples. Testing was done at three locations along the stream. Szal added that fall is the best time to undertake this kind of monitoring.
“This technique works because of the life-cycle of the organisms we’re studying,” she said. “In the spring, many of them hatch and take wing….And it’s so hard to work in April, through the high flows and ice melts. In the fall, we have a representative population; they’ve laid their eggs and they’ve started their development. They will spend the winter here.”
Ussach said volunteers may return to Mill Brook sometime next year for additional monitoring and a report will be put together and posted on millerswatershed.org.
“We’ll share the results with our members,” he said. “We’ll put it on the website, and we’ll share it with the town of Athol.”
Ussach said results will also be sent to Katherine Antos, undersecretary for decarbonization and resilience for the state Executive Office of Energy and Environmental Affairs, whom he met at the ribbon cutting for Mill Brook Crossing.
“So, these results are going to be sent very high up the food chain,” he said.