This ecoregion is a long, narrow complex of ecosystems that occupy the valley of this major geological fault that runs between the Columbia Mountains and the Rocky Mountains. The Southern Rocky Mountain Trench is a linear, steep-walled, faulted valley about 480 km long. The valley floor is relatively level and can vary in width from less than 1 km to 20 km. The headwaters of a number of large rivers lie in the trench. The northern limit of the ecoregion is around 54° N latitude and runs south to the border with western Montana. Climate tends to become warmer and drier moving from north to south. The mean annual temperature for the ecoregion is approximately 4.5°C with a summer mean of 14°C and a winter mean of -5.5°C. The mean annual precipitation is less than 500 mm in the southern end of the ecoregion around Windermere and Cranbrook, and 800-1000 mm in the central portion in the vicinity of Kinbasket Lake. Valley bottom vegetation ranges from bunchgrass, ponderosa pine, and Douglas-fir in the south, to western red cedar and western hemlock in the central portion, and to white and black spruce and lodgepole pine in the northern portions of the ecoregion. Underlain by Palaeozoic and Proterozoic strata, the trench is covered with a variety of glacial deposits including ground moraine, outwash plains and terraces, drumlins, eskers, glacial lake terraces, and recent alluvium. Large floodplains and wetlands have been formed by several large rivers that drain into and meander along the valley floor of the trench. Dystric and Eutric Brunisolic soils developed on steeply-sloping colluvial and morainal deposits dominate upland sites and well-drained valley floors. Gleysolic and Mesisolic soils occupy areas of wetlands. Characteristic wildlife includes elk, moose, mule and white-tailed deer, bighorn sheep, grizzly and black bear, cougar, coyote, grouse, and waterfowl. Land uses include forestry, water impoundment, grazing, hunting, recreation, livestock, forage crop production, and tourism. Some main communities are Cranbrook, Kimberley, Invermere, and Golden. The population of this ecoregion is approximately 45 000.
This ecoregion is part of the Montane Cordillera ecozone.