The Portage Diversion is a water control structure on the Assiniboine River in Manitoba, Canada. The project was made as part of a larger attempt to prevent flooding in the Red River Valley. The Portage Diversion diverts some of the flow of water in the Assiniboine River to a 29 km long diversion channel that empties into Lake Manitoba. This helps prevent flooding on the Assinboine down river from the diversion, including in Winnipeg, where the Assiniboine River meets the Red River.
The diversion cost $20.5 million dollars to construct. It was completed in 1970. The control dam is 35 feet (11 m) high and 1,400 feet (430 m) long. It has 2 gates that allows 14,600 acre-foot (18,000,000 m³) storage.