AMHERST — Just after Memorial Day, the first round of testing to determine the E. coli levels at Puffer’s Pond revealed the bacteria in the water exceeded acceptable state standards, requiring the temporary closing of the site for swimming.

A week later, though, and with drier weather, the next round of tests from both the south and north beaches showed the bacteria levels within a safe limit, allowing the pond to be reopened for swimming.

But with the pond closed for swimming for much of summer 2024, town officials are taking proactive steps to figure out why what had once been a rare occurrence, with almost no closings of the pond until summer 2018, have become commonplace.

Assistant Town Manager David Ziomek said one strategy is to do more testing along the Cushman Brook, all the way to the Leverett line, to see if runoff from private septic systems, farms and catch basins may be exacerbating the condition of the pond. Six sites are joining the two beach testing sites.

“That should help us paint a much better picture of where the contaminants are coming from,” Ziomek said.

Doing more testing should also be more accurate, Ziomek said, showing specific causes of contamination, such as if geese have been present in one area or if a family has thrown out a diaper from the beach. Animal or human waste, typically cow or horse manure, septic systems and leaking sewers are often the most likely culprits.

Already this year, the swimming hole in the Fort River off Stanley Street, near Kiwanis Park, is closed. Ziomek said a semi-permanent sign has gone up at the “jump bridge” warning people to stay out of the water, with contamination believed to be coming from upstream.

“We know the water quality in the Fort River won’t be up to acceptable levels,” Ziomek said.

Part of the challenge for the town at Puffer’s Pond, built as a factory pond in the 1800s, is part of a conservation area is always open for hiking, walking and fishing. This is unlike other similar ponds, like the Belchertown Town Beach, which Ziomek said can be fenced off.

In general, though, with warmer air and water, more rain and heavy rain flushing out of the watershed, some of the problems can’t be controlled.

A new round of bathymetry measurements are expected to be done, with the last showing that the pond is 11 to 12 feet at its deepest, anticipating that new measurements will show continued filling in below the surface. “The pond is getting shallower due to sediment,” Ziomek said.

There will also be core sampling to get the depth and composition of the sediment, and whether contaminants are embedded there from the paper mills that once lined the Cushman Brook.

A dredging project would make the pond deeper and would cool the water. The town has put a $2 million placeholder in the five-year capital plan in anticipation of this work proceeding, Ziomek said.

In 1986, 100,000 cubic yards of material were removed during a dredging, while a partial dredging was done more recently.

Ziomek said the town is also trying to get more involvement from the University of Massachusetts, while a small working group, or task force, meets every two weeks to look at options.

Amherst is receiving $250,000 to design repairs for the 1895 dam and the 6-foot high dike, with the money coming from the state’s Executive Office of Energy and Environmental Affairs’ Dam and Seawall Repair or Removal program.

Scott Merzbach can be reached at smerzbach@gazettenet.com.