It's lurking under the water, and sinking the property values at Smith Mountain and Claytor Lakes.
Friends of Claytor Lake are trying to call attention to Hydrilla.
It's a plant that's grown so dense, some residents can't get their boats out of their dock or swim near their property.
And they're worried tourism is going to be a problem.
Several groups are working to address the problem.
Homeowners and visitors agree the sooner the better.