The Oldman River is a heavily regulated river flowing through the arid, agricultural region of southwestern Alberta. Although population in the region is relatively low — Lethbridge is the largest city — water use is very high, primarily for irrigation to supply numerous farms and ranches with adequate water during the growing season. The Rocky Mountains generate up to 90 per cent of the streamflow; however, the amount of water moving along the river varies from year to year and season to season. Additionally, droughts are common, and numerous dams, weirs, and reservoirs on the Oldman and its tributaries are used to manage the high water demand. The Oldman River is also used for hydroelectricity generation, municipal drinking water and recreational activities including fishing, boating and camping.