EASTHAMPTON — The Nashawannuck Pond — at the forefront of one of the city’s iconic views with Mt. Tom looming in the background — developed a cyanobacteria bloom this summer, but further investigation showed the bloom was not toxic.
Like many lakes and ponds in the recent past, Nashawannuck has experienced an increase in the number of algae blooms as a result of warmer temperatures, a phenomenon that can occur in water bodies that are shallow, stagnant and rich in nutrients from agricultural runoff including fertilizer.
Some of the blooms contain cyanobacteria — microscopic single-celled organisms also called blue-green algae — which can be harmful to people and pets. The Easthampton Board of Health first saw visual indications of these greenish-blue blooms in Nashawannuck in 2019.
At large volumes cyanobacteria can emit harmful toxins, according to Melissa Langley, Connecticut River Conservancy’s lab and monitoring coordinator.
“We as a scientific community don’t necessarily know which of these toxins are harmful to people or how harmful they might be,” Langley explained. “So depending on the type of cyanobacteria, there are a lot of them, some of them create toxins that damage your liver and there are neurotoxins that can make you dizzy. They can cause gastro symptoms, but not all of them are harmful to people.”
Years of effort from the city and the Nashawannuck Pond Steering Committee, which acts as the city’s pond management team, have helped mitigate the bacteria levels and algae blooms. The committee started monitoring the pond’s cyanobacteria levels with the CRC in 2022. Each May, the CRC measures levels every two weeks until the fall, along with the neighboring Rubber Thread Pond.
The testing process measures certain photosynthetic pigments that indicate potential cyanobacteria blooms. This year, the July 22 report showed that a cyanobacteria bloom formed in three different locations in Nashawannuck Pond.
However, according to the steering committee, further lab testing showed the bloom was not toxic. Beth Tiffany, a member of the steering committee, said they followed protocols and had the water tested further at a private tester.
The Aug 5. CRC report shows the levels dropped below the bloom threshold and the second-to-last test of the year on Oct. 14 also showed levels were well below the threshold, as expected when the weather gets colder.
The red line in the following CRC graphs represent the threshold for a potential presence of a cyanobacteria bloom — the July 22 report is on the left and the Aug 5. report is on the right. There were three testing locations in Nashawannuck Pond, shown at the top of the graphs.
The CRC will be publishing a more comprehensive report of its findings within the coming weeks, compared to these one-day samples.
CRC Water Quality Assistant Jodie Berezin said there is not extensive research on cyanobacteria, but blooms typically stay below toxic thresholds.
Blooms are generally seen in July and August when it is hotter, there’s less rain and water levels are lower. Besides warmer temperatures, bacteria levels increase due to nutrient overloads from fertilizers and herbicide treatments. Langley said an herbicide treatment to the pond — on July 10 — could have contributed to higher levels.
“In addition to the nutrients, especially it’s heat,” Langley said about the blooms. “So we see issues like this getting worse with climate change when it’s hotter for longer.”
Easthampton Conservation Agent Eva Gerstle said the steering committee typically does one or two herbicide treatments a year, a necessary measure to help reduce invasive vegetation.
Gerstle said the city works with abutters of the property to make sure they are compliant with the state Wetlands Protection Act, providing regulations on private development near water bodies. She said it is crucial to also protect the many runoff streams that extend from the pond.
A mix of tactics are used to reduce cyanobacteria by the steering committee. Volunteers pull invasive plants, attempt to limit nutrient overloads and practice one tactic that involves placing onion bags filled with barely straw in the pond.
The barely works by slowly decomposing over the course of the summer, releasing molecules that prevent cyanobacteria growth.
There were 25 barely bags put in the pond this year, more compared to those past. Chair of the Steering Committee Paul Nowak feels the extra bags helped prevent extensive cyanobacteria growth.
“We put a few more in this year than we did in the past as a little extra measure and so far it’s been very successful,” he said.
The idea for the barley straw project came from Dr. R. Allison Ryan, a retired physician and neurologist that has researched invasive plants. In the past decade, she found that algae blooms have been seen in the same places where water chestnut infestations — common in Nashawannuck — have been found.
According to previous editions of the Gazette, Ryan found through her research, that the toxic cyanobacteria blooms can cause acute and chronic health hazards to plants, animals and people. Cyanobacteria can produce the neurotoxin BMAA (also known as beta-N-methylamino-L-alanine), which has been linked to neurodegenerative diseases including Lou Gehrig’s disease, also known as amyotrophic lateral sclerosis or ALS.
For Tiffany, the continuous monitoring of the pond is vital.
“It’s a focal point and it’s at the beginning of our cultural district,” she said about the pond. “It’s good for business, people sit there. It’s just a beautiful place to be.”
More information can be found at the Nashawannuck Pond Steering Committee’s website.
Other pond news
At the City Council’s Nov. 5 meeting, councilors unanimously approved of providing approximately $78,000 to rebuild one of the retaining walls on the shore of the pond.
There are six retaining walls around the border that provide stability to the shore and prevent sediment from crumbling into the pond. This particular retaining wall is on the shore inside Nonotuck Park, directly across the pond from the boating dock off of Water Lane.
At the meeting, Precinct 3 Councilor Thomas Peake said the “retaining wall is doing less of a good job retaining every single year, it’s degrading.”
The wall will be replaced with a sturdier, stone wall that is expected to last at least a generation. The funding comes from open space funding reserves.
At the meeting, Gerstle lauded the work of the steering committee for creating the funding application and identified this wall in dire need of reconstruction.
Tiffany said while the pond was previously used for recreational swimming at the boating dock, this cannot happen anymore due health and safety regulations.
This article was edited to show a cyanobacteria bloom was detected though it was not toxic, rather than no bloom being detected. The July 22 graph was added as well.