PITTSFIELD, Mass. — Pesticide treatment is not needed at Onota Lake as water testing continues to come up negative for zebra mussels.

Park, Open Space, and Natural Resource Program Manager James McGrath attributed the September detection to the shell of a dead zebra mussel that likely came through on a boat. At this time, the lake is not believed to have an infestation.

"What we think has happened is there was probably a boat that was launched at the boat ramp last summer, it probably had a dead zebra mussel shell on it, stuck to it, and when it launched right off the boat ramp that shell sort of fell off the boat and was sort of among the rocks off of the boat ramp," he explained to the Parks Commission on Tuesday.

"We think that is what happened because we had divers that we hired on multiple occasions to look for adult zebra muscles just to see if we were missing anything so we had divers do massive sweeps of the lake at great expense. We never found any. The last series of dives that we did just maybe a month ago, we found the shell. It was actually two shells. They were very, very, very tiny. We think what happened was those shells near the boat ramp were shedding DNA as they were decomposing."

Zebra mussel mitigation efforts began in 2009 when the invasive species was found in Laurel Lake in Lee. From then to last fall, the city was in prevention of invasion mode, and after the detection, it was in rapid response mode with the intent of eradicating any pioneer infestation.

The positive detection "caused a red flag to go off," McGrath said, because the city was thought to do a great job in preventing zebra mussels from entering its lakes through monitoring and education.

"The one detection, what that meant for us is a heightened vigilance around our efforts to prevent zebra mussels infestation, that means we really need to be mindful of where boats are coming from before they launch into the lake," he explained.

With help from the state and the Lake Onota Preservation Association, there has been regular sampling to confirm the existence or nonexistence of the invasive species to determine the path forward.  In April, the Conservation Commission gave them the go-ahead to use EarthTec QZ within a specified treatment area but that will not be needed.

Now, the city will proceed with a heightened awareness and look to bring a boat wash project to fruition.

"Of course, for the past decade, we've had program monitors that both Onota Lake and Pontoosuc Lake all summer pretty much seven days a week from 7 a.m. to 7 p.m. Everyone who launches a boat invariably gets intercepted by a city person finding out where's the boat been, have you decontaminated if you need to, how did you do that," McGrath said.

"We also do a lot of social media outreach, there's a lot of outreach to folks that live around the lake so we've got a strategy that we've been working on for a number of years and it seems to be working."

Last year, a $75,000 design for the boat wash was granted Community Preservation Act funding. The commission was assured that the city has not dropped the ball on it.

Resident John Gowdey submitted correspondence to the commissioners for this meeting urging the completion of the project — especially since the zebra mussel scare.

"Any updates to the commission since November have been minimal regarding the infestation and in particular the Boat Wash," he wrote.

"Hopefully, recent tests will result in a negative not positive test but either way the Boat Wash needs to be installed."

McGrath detailed hurdles with location, design, and construction costs. Planners have observed that Burbank Park does not lend itself well to a boat wash because of the scale and magnitude needed.

"We feel like we have a little bit of breathing room because we don't have zebra mussels at Onota. Our boat ramp monitors, our signage, our social media outreach, and all the other things that we're doing seem to continue to be what is working for us. We remain vigilant and we know that we can't let our foot off the gas," he said.  

"We probably really do need to implement a wash station, if not at the park, proximate to the park. We also know we've got Pontoosuc Lake that is another water body we're concerned about. So there's a lot of questions that were that are still being raised as we think about what it means for us to offer a boat wash."

The city needs to figure out how the boat wash can be staffed, what it will cost annually, and what the capital cost will be as prices increase.

"That's the long story of saying that we dodged the bullet last September. We don't have zebra mussels so we don't feel that it's critically important that we implement boat washing immediately but it's something that is on the horizon for us and it's something that I'm very mindful of that we need to get to the finish line. There's a lot of outstanding questions, McGrath said.

"The state is a strong partner with us along with the Lake Onota Preservation Association. We're all trying to figure this out because it's a really complicated issue but in the interim, while this conversation is happening, we are relying on our boat ramp monitors in a stepped-up way this year. They've got sort of a new direction and sort of approach to how they're operating and the questions that are asking."