Oldman RiverCypress, Lethbridge, M.D. of Pincher Creek, M.D. of Ranchland, M.D. of Taber, M.D. of Willow Creek · 128.1 of 428.6 km public · Cutthroat trout, Rainbow trout, Brown trout, Bull trout
Ole LakeClear Hills · lake · Stocked lakes and ponds
Olson CreekM.D. of Greenview · 18.9 of 18.9 km public · Rainbow trout, Bull trout
Onion CreekClearwater · 18.7 of 18.7 km public · Cutthroat trout
Orchard CreekYellowhead · 6.1 of 6.1 km public · Rainbow trout, Brook trout
Otauwau RiverM.D. of Lesser Slave River · 132.7 of 132.7 km public · Arctic grayling
Otter CreekClearwater · 6.1 of 6.1 km public · Cutthroat trout
Otter RiverNorthern Sunrise · 136.6 of 147.9 km public · Arctic grayling
Outpost LakeCardston · lake · Stocked lakes and ponds