St. Mary River

The St. Mary drains the Purcell Mountains east to the Kootenay at Fort Steele, through St. Mary Lake and past Marysville below Kimberley. It is catch and release for every trout and char, with a bait ban, and it is Class II classified water. Wild westslope cutthroat of 30 to 45 cm are the main fish, the lower river holds a few big rainbows, and bull trout follow the cutthroat. The lake in the middle settles silt out of the runoff, so the river below it clears sooner than the water above it.

Below the lake the river is a mix of long riffles, ledges and pools through forest and ranch land, floated from the pumphouse access down to Wycliffe, and from Wycliffe to the Kootenay. Caddis come off from the opener on, and late summer brings green drakes, mahogany duns and hoppers, with blue-winged olives into October. Above the lake it is small mountain water reached on forest roads, best waded in August and September. The only live gauge sits above the lake, below Morris Creek, so it reads the upper river directly and the lower river only by its trend: the lake and the creeks below it add a lot of water. At that gauge the upper river wades well under about 8 m³/s and runs past 30 in a big June.

The St. Mary sees less pressure than the Elk, and Kimberley and Cranbrook are both close, so it makes an easy half-day float. Much of the land along the lowest river is ʔaq̓am (Kootenay Indian Reserve No. 1). Float through it and stay off the banks there unless you have the community's permission. If the river is high or off color, the Kootenay is a few minutes away, and the Bull and the Elk are within an hour.