Decades-old milfoil mats removed from Lake George

By Gwendolyn Craig

Since at least 1985, the invasive Eurasian watermilfoil has populated Lake George’s waters, which also means officials have tried many different ways of getting rid of it.

One of those ways is now in the garbage, literally.

Milfoil is a long, stringy plant that grows quickly and grows new plants from chopped up pieces. It’s usually transported by boats from other infested lakes.

At first, Lake George Park Commission records show, the way to get rid of it was pulling the plants from the water by hand. But then around 1990, officials tried stifling milfoil with plastic mats, about 100-feet long.

David Wick, executive director of the Park Commission, said management contractors would put the mats down in one dense area of milfoil, then move it the next year to a new location. The mats help keep the invasive plants from photosynthesizing by blocking out the sun.

The process worked, sort of.

“But there was always money to put the mats down, and never money to take the mats out,” Wick said. Now, funding from the Park Commission and the Lake George Association will remove them.

Since the ‘90s, milfoil management has progressed and the Park Commission now relies on diver assisted suction harvesting to take milfoil out of Lake George. That involves divers uprooting milfoil plants and shooting them through a kind of vacuum hose underwater, sucking up any plant fragments with it.

AE Commerical Diving, the company contracted to do the milfoil work now, switched gears earlier this month and removed old mats instead of milfoil.

“It’s definitely time to take the mats out because basically, it’s garbage on the bottom of the lake at this stage,” Wick said.

In approximately 55-degree water, a diver dipped down to the bottom of Tea Island Bay at the end of October and pulled up a part of one of the old plastic mats. He attached a hook to it and a nearby boat dragged the mat from the water.

The process continued for several mats.

Ben Sheldon, operations manager for AE Commercial Diving, said the mats are dragged backwards causing them to fold over and dump the remaining debris toward the bottom of the water column.

Some of the mats were so covered in sediment that Wick said staff had put more mats on top of hidden ones. Sheldon and his divers found those, too, and removed them from the lake.

Most of the mats removed were concentrated at the southern end of Lake George, and Wick said those spots will be monitored for milfoil closely next year. That’s because there’s now open, fertile lake bottom.

“We want that to repopulate with natives and not with milfoil, so we’ll stay on top of this a couple of times at least, next year,” Wick added.

2021 will also mark the end to a $600,000 milfoil management grant the Park Commission has for removing the invasive species. Wick and Sheldon said they are close to removing all of the densest milfoil beds in the lake.