Garrison Diversion Project, or more simply Garrison Diversion, is the common name of an undertaking of the Bureau of Reclamation with the official title of, "Initial Stage, Garrison Diversion Unit, Pick-Sloan Missouri River Basin Program."¹ The basic scheme of the Garrison Diversion is the withdrawal of water from the Missouri River for irrigation of 250,000 acres of farmland in semi-arid areas of central and north-central North Dakota.² What gives the project international significance is that about 75 percent of the area to be irrigated is situated in the watersheds of the Souris and Red Rivers, which flow into Canada.³ The irrigation return flows, that is, the runoff and seepage of the water used for irrigation into these rivers, will affect both the volume and the quality of the water that flows across the international boundary.

The predicted environmental consequences of this project are of serious concern to Canada. The additional volume of water will increase the hazard of flooding and may also alter or destroy both fresh-water and brackish marsh habitats of waterfowl and other wildlife. Changes in the water quality of the rivers will affect municipal and agricultural uses and will aggravate an already serious problem of eutrophication in Lake Winnipeg.