Kootenay River - Ecology

Ecology

The Northwest Power and Conservation Council divides the Kootenay River watershed into six biomes: aquatic (rivers and lakes), riparian zones, wetlands, grassland/shrubs, moderately wet forest, and dry forest. The forested zones extend through the alpine and subalpine reaches of the watershed, while grasslands dominate the low terraces and plateaus surrounding the river, especially in the Lake Koocanusa area and the Montana-Idaho portion of the watershed. In the Canada portion of the watershed, an alpine meadow ecozone occupies most of the high ridges and valleys of the mountains.

In the Canadian portion of the Columbia Basin, almost half of which is part of the Kootenay River basin, there are 447 species of terrestrial vertebrates. Most of the Kootenay basin lies within the Columbia Glaciated ecoregion which encompasses much of northeastern Washington, northern Idaho, northwestern Montana and southern British Columbia. Fish fauna in the region are largely shared with those of the Columbia Unglaciated ecoregion to the south, which has about fifty species of fish and only one endemic species. There are no endemic fish within the Columbia Glaciated region itself.

Riparian vegetation is mostly found along the lower two-thirds of the Kootenay and many of the tributaries that join within the United States. The other sections of the river flow through far more rugged terrain and are characterized by braiding, low nutrient content, shifting channels and coarse sediments, making it difficult for riparian zones to be established, as is with most of its upper and lower tributaries. Wetlands are found primarily where the river broadens into a series of sloughs, side-channels, marshes and small lakes before entering Kootenay Lake. This biologically diverse area, the Kootenay Flats, once supported over 1 million migratory birds every year, before the river was diked and many of the wetlands converted to agriculture.

Naturally, the Kootenay has a high sediment content because of high erosion of glacial sediments in the mountains. Because of the steep rapids and falls between Kootenay Lake and the river's mouth, the Kootenay (with the exception of its tributary, the Slocan River) has never been a significant stream for the annual runs of Columbia River salmon. However, landlocked salmon inhabit the upper reaches of the river above and in Kootenay Lake. This is attributed to a Kootenay River flood a long time ago, before the construction of any dams on the Columbia (Columbia River dams now block salmon from reaching any of the salmon run streams above Chief Joseph Dam ) which overflowed into Columbia Lake. It was with the creation of this temporary body of water that salmon somehow managed to swim over the submerged Canal Flats and into the Kootenay, where they became trapped.

Populations of large land mammals such as caribou, moose, deer, elk, have been declining dramatically since the reintroduction of wolves. Species almost entirely gone that were once common in the area include the white-tailed jackrabbit, pygmy short-horned lizard, band-tailed pigeon and passenger pigeon. After exploitation of the Kootenay basin by fur trappers, the beaver population was nearly exterminated as well.