Week 2 Hand Harvesting Update
Aqualogic’s team of SCUBA divers returned to Chateaugay Lake on July 28th for their second week of hand harvesting this season, working in the Upper Lake. The team was deployed to harvest the beds that had been planned for herbicide treatment this year—Beds B, D, and H as shown on the map. The ProcellaCOR treatment was not carried out because the Eurasian milfoil had not emerged sufficiently by the treatment deadline of June 30. They also revisited Bed I along Indian Point.
The divers spent 2 1/2 days harvesting the northeastern shoreline, progressing from Bed D east of the Sand Bar to Bed C off Owlyout Creek and Bed B along Sunset Road. In Bed D, they found numerous small plants at five-foot depths, with some starting to reach the surface and form a canopy. There were signs of “boat scalping,” with rooted fragments lying on the bottom. Harvesting areas where plants are reaching the surface is an important step to prevent scalping and spread.
They found sparse milfoil in Bed C, where the bottom is very sandy. There was also little milfoil in the northern part of Bed B, where it has been moderate-dense in the past. None of these areas had been hand-harvested previously. In addition to Eurasian milfoil, a small amount of curlyleaf pondweed, another invasive, was removed from Bed D.
Mid-week, the divers moved to the south basin of the Upper Lake and harvested Bed I along Indian Point, which has been hand-harvested since 2016. Divers had been removing one-two tons of EWM in a week in Bed I until last year, when it was reduced to one-third ton. This year, the divers found a small amount, mostly toward the southern part of the bed (7 gallons/16 pounds).
The divers also harvested Bed H, Deep Bay, immediately north of Indian Point, which had not previously been harvested since it is not subject to heavy boat traffic, though known to have moderate and dense milfoil. They harvested some moderately dense areas, removing some curlyleaf pondweed as well as milfoil (25 gallons/58 pounds).
At the end of the week, the divers returned to the northeastern shoreline to harvest an area where milfoil had been spotted between Beds C and D. The northeast shoreline had the most growth of milfoil found and harvested during the harvest week (59 gallons/136 pounds.
The milfoil conditions in the Upper Lake mirror those observed in the Lower Lake during the first week of harvesting. There is reduced—even sparse—growth in areas that previously supported moderate and dense beds. Several factors could be at work. A 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 may be working in concert to dampen milfoil growth and spread. It’s something that the CLF and others interested in lake ecology and aquatic plant growth are watching closely.
