How did a invasive mussel species invade a Western Mass. lake?

The Boston Globe · Bryan Hecht · 2026-11-06 11:00 UTC

Pittsfield officials began spraying pesticides to kill zebra mussels this week, amid rising concerns over the spread of the species among state conservationists.

An invasive species known as the zebra mussel has been found in Pittsfield, raising concerns the freshwater shellfish may be spreading in the Berkshires and could threaten the health of a number of area lakes, experts said.

After identifying a possible infestation at Onota Lake in Pittsfield, city officials last week warned residents not to swim in the water while they use pesticides against the unwanted mollusks.

Pittsfield also employed such control efforts two years ago to prevent the mussels from growing in the lake’s murky depths, according to Jim McGrath, a natural resource manager with the city’s parks department.

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