Approximately forty-seven non-native, aquatic nuisance species (ANS) have become established in Lake Champlain. Nearly 4 times this number have invaded the Great Lakes. Available evidence strongly suggests that new species will continue to invade Lake Champlain via a number of vectors, including canal connections to the Hudson Estuary and the Great Lakes. An analysis of published reports indicates that the Champlain Canal is the single largest known vector of Lake Champlain ANS, likely serving as the conduit for at least 16 taxa. While an optimal barrier would be 100% effective at preventing transport through the canal, this should not be the criterion for success. Even an 80% reduction in the probability that a species could enter Lake Champlain via the Champlain Canal represents significant progress in protecting the ecology of the Champlain basin. Six canal barrier ideas were proposed and examined from the standpoint of feasibility. Preliminary costs and benefits were also described. Although additional research and economic analysis is called for, physical/mechan​ical modification of canal and or locks may represent the best alternative. Modifications could consist of limited hydrologic separation with provisions for overland transport of recreational vessels. The low number of commercial vessels still using the system might be accommodated with the use of graving dock or seasonal lockage restrictions. A behavioral barrier (electrical, bubble, sound, strobe light - alone and in combinations) was found to be a good second alternative, though no protection against plants and invertebrates would be realized.