DERBY – Salem Lake in Derby has a clean bill of health once again; nothing has gotten past the watchful eye of the lake monitors, patrollers, and professional diver Shawn Bickford. But its future remains uncertain because of all the risks in surrounding areas.Several lakes in Vermont are contaminated with invasive species, including Lake Memphremagog and Lake Champlain.Every year the state requires a final report and a projected budget from the Salem Lakes Association on the health of the lake. Salem does not have any invasive species of the plant or animal kind, a bit of a rarity in the state.Andy Major, president of the association, knocks on wood for the good fortune, and has his fingers crossed that the preventative program in place, which includes an educational piece, will continue the success.Once invasive, non-native species such as Eurasian water milfoil take root in a lake, they swiftly take over and are about impossible to eliminate. They choke out native species, make it impossible for most fish to survive, and get in the way of recreational activities such as swimming. The species called zebra mussels take over and can plug up water pipes for drinking water or cause other problems.The program at Salem monitors boats, trailers, and vehicles of every kind before they enter the lake. Inspectors examine the crafts and equipment before they're allowed into the water. The program is funded through the state, the town and the lake association.Bait is also inspected as some people unknowingly use an invader bait, which leads to introducing the unwanted species to the lake.If something is found to have an invader on it, inspectors recommend that the owner head to the car wash. In some cases the inspector will manually clean the contamination. Major warns that it is illegal to transport invasive species in Vermont.Over the summer, 709 boats entered the lake, eight of which were contaminated with an invasive species such as milfoil or zebra mussels.Humans are the number one threat for bringing the invaders to the lake, but not the only threat. Birds also contribute to the problem. The Salem area is a place where large birds like to gather including blue herons and bald eagles. Of new concern in the number of Canadian geesenear the lake. Other concerns from birds are E.coli contamination and, especially from geese, “swimmer’s itch."The Salem Lakes Association began in 1985 with the goal of preserving the lake and keeping it clean. The late David Wood started the program.The lake is known for its large walleye. In recent years, fishing derby winners have found the largest walleye in Salem.Support for this project is provided in part by Vermont Department of Environmental Conservation. For more information, visit