CAROGA — For decades, scuba divers have hand-picked invasive plants from the depths of Caroga Lake. It's a dangerous mission. And the town-funded program still isn't enough to ward off Eurasian watermilfoil, maintained Walter Hogan, a West Caroga Lake Association member. "You can't just sit around and not do things differently year after year after year and costs are rising, rising, rising," he said. Back in March, Hogan applied for a $50,000 grant from the state Department of Environmental Conversation to try out a new herbicide on the lake, ProcellaCOR. If awarded, it would fund a two-year chemical treatment study.…