Reston Association is urging residents to avoid using water from Lake Thoreau for irrigation until mid-October.
The guidance comes after Aquatic Environment Consultants treated Hydrilla, an invasive aquatic species, on the water. Conducted monthly and typically around the middle of the month, treatments will continue throughout the summer to maintain low levels of herbicide in the water.
The company was contracted to treat Hydrilla when it became a “nuisance” two years ago, according to Ben Rhoades, RA’s watershed manager.