The South Saskatchewan River Basin is comprised of four major sub-basins: Red Deer River, Bow River, Oldman River, and the South Saskatchewan River. All of the basins begin in the Rocky Mountains and generally flow eastward through the foothills and the prairies. The combined watershed of the basins is 121,095 km2, of which 41% is the Red Deer sub-basin, 22% is the Oldman, 21% is the Bow, and 16% is the South Saskatchewan.
The Oldman River begins in the southern Rockies and flows out onto Alberta's foothills and then the prairies. The Oldman drains into the South Saskatchewan River at the confluence of the Bow River. The South Saskatchewan River ultimately makes its way to Hudson Bay.
- In 2006, the Oldman River sub-basin became one of three southern basins to be closed to new surface water allocations.
- Approximately 87% (nearly 2 million dam3) of total surface water and groundwater is allocated to agriculture.
- Of farms in the Oldman sub-basin, 44.1% are cattle farms, 15% are grain and oil seed farms, and 10.8% are wheat farms.
- 42 district licences allocate approximately 1.7 million dam3 and represent approximately 90% of total allocation in the Oldman Basin.