Exotic plant species that are potentially a threat to the Tri-Lakes include Eurasian milfoil, starry stonewort, and curly-leaf pondweed. Early detection and rapid response are key to effective control of invasive aquatic plant species. Each year, biologists from Progressive Companies conduct multiple surveys of the lakes to identify exotic plant locations and targeted herbicide treatments are carried out to control nuisance plant growth. The herbicide treatments require a permit from the Michigan Department of Environment, Great Lakes, and Energy.