The primary headstream of the South Saskatchewan River system, originating at the Bow Glacier and Wapta Icefield (~2,310 m) and flowing 587 km through Banff National Park, Canmore, and Calgary to join the Oldman River near Grassy Lake. The river is central to the history and ecology of southern Alberta.

Glacial origin and rock flour. The Bow begins as cold, sediment-rich meltwater from the Wapta and Waputik icefields. Glacial erosion produces fine silt (rock flour) that stays suspended in the water; giving Lake Louise, Bow Lake, and the river itself their distinctive milky turquoise colour. The intensity peaks in summer as meltwater volume increases.

Indigenous names. The Stoney Nakoda called it Ijathibe Wapta (“a place where people made bows out of Saskatoon saplings”) and Mînî Thnî (“Cold Water”); the Blackfoot called it Makhabn (“river where the bow reeds grow”). Sir James Hector of the Palliser Expedition conducted the first European scientific survey of the Bow headwaters in 1858–1859. The English “Bow” reflects the reeds used by Indigenous peoples for hunting equipment.

Course. From Bow Lake the river flows past Lake Louise; receiving Louise Creek (draining the lake, fed by the Victoria Glacier) and the Pipestone River (source of red argillite for Stoney Nakoda calumets); through the Bow Valley, past Banff and Bow Falls, and onward to Calgary. The Icefields Parkway parallels the upper reaches; passing Bow Lake, Bow Pass, and Peyto Lake before crossing the Continental Divide at Saskatchewan River Crossing. The Bow Valley Parkway runs alongside the river between Lake Louise and Banff, passing the ghost town of Silver City at Castle Mountain.

Ecology and management. The upper Bow provides habitat for Westslope Cutthroat Trout and Bull Trout; both federally listed as Threatened. Dams, culverts, and stormwater runoff have fragmented habitat and degraded water quality. The Lake Louise headwaters are increasingly valued as thermal refugia as climate change warms downstream reaches.

Recreation. Popular for trout fishing, rafting, and paddling. The Bow River Loop Trail offers an easy walk through the riparian zone near Lake Louise. The river provides drinking water for downstream communities.