Zelma Reservoir is a reservoir in the Canadian province of Saskatchewan in the Rural Municipality of Morris No. 312. It is about 17 kilometres (11 mi) east-southeast of the town of Colonsay. The reservoir was built in 1967 as part of South Saskatchewan River Project. That project, originating at Gardiner Dam of Lake Diefenbaker, involved the building of aqueducts, canals, and a series of reservoirs to supply water for irrigation, consumption, and industry. Other reservoirs in the system include Broderick Reservoir, Brightwater Reservoir, Indi Lake, Blackstrap Lake, Bradwell Reservoir, and Dellwood Reservoir.