Week 1 Hand Harvesting Update

Aqualogic’s team of four SCUBA divers arrived at Chateaugay Lake July 21 to start the first of two weeks of hand-harvesting. Overall, the divers found very little Eurasian milfoil in both the areas that had previously been hand-harvested and the areas treated with herbicide last year. The combination of repeated hand-harvesting in areas of high boating traffic, last year’s ProcellaCOR treatment in the most infested stretch of the Narrows, and environmental factors like heavy spring rains and high water that suppress growth, are working to dampen milfoil growth and spread.

This season, work began on the Lower Lake, where the goal has been to maintain a cleared boating lane through the Eurasian milfoil bed that had developed across the lake at the mouth of the Narrows.  Since harvesting began here in 2018, the amount of milfoil has been greatly reduced. Initially, divers would remove 1-2 tons of milfoil in a week of diving, which was down to a half-ton last year. This year, the divers found very little milfoil, mainly a small cluster of plants on the western side of the bed. They also checked the shoreline to the immediate north and south and found no milfoil, but healthy native plants.

During the second half of the week, the divers moved to the Upper Narrows to check the stretch south of the Narrows bridge that had been treated with ProcellaCOR last year. They removed a small amount of milfoil by the channel area across from the boat launch. They also removed a patch of curlyleaf pondweed, another invasive that has been found sporadically around the lake (see photo).  

On Thursday, they swam the north side of the sand bar and removed a small amount of milfoil (about 12 pounds). On Friday, they checked the bed to the immediate south of the sand bar that had been treated last year and found no milfoil. They proceeded easterly along the north shore of the Upper Lake removing another cluster of curlyleaf and harvested a patch of moderately dense milfoil in Bed D, which had been slated for ProcellaCOR treatment this year. The divers confirmed what our top-water volunteer scouts had reported about the overall reduction in milfoil evident so far this year.