New Hampshire Department of Environmental Services officials say they have discovered a dense infestation of milfoil in a popular pond in Bow.
Officials say the infestation found in Turee Pond is so dense that it suggests milfoil's probably been present in the pond for three to four years.
Milfoil is an invasive plant found in bodies of fresh water.
Officials say Turee Pond gets a high number of boaters, any one of which could have introduced milfoil from another contaminated body of water on a boat or fishing gear.
Outdoor enthusiasts are urged to wash and dry boats and gear after leaving a body of water.
Officials say they have detected invasive specials in 81 New Hampshire lakes, ponds and rivers.