Since the 1890s, 9,300 hectares of the 16,000-hectare Kootenay River floodplain have been dyked for agriculture, eliminating the natural habitat. Conservationists and biologists recommended that the remaining valuable wetland be saved as a wildlife reserve. The Creston Valley Wildlife Management Area (CVWMA) was created in 1968, but the area now must be intensively managed within 17 separate dyked compartments. Pumps manipulate water levels, and some sections may be temporarily drained to control aquatic vegetation and recycle nutrients. Other areas are planted to lure birds away from nearby crops.
The Duncan Dam was built 10 kilometres above the north end of Kootenay Lake in 1967, and in 1972 the Libby Dam was built on the Kootenay River in Montana. Both dams have profoundly affected the ecology of the Kootenay River and Kootenay Lake. They eliminated much fish spawning habitat and riverside wetland habitat. Most of the silt and nutrients carried by these rivers settled out in the reservoirs above the dams and was not carried down to their floodplains. Kootenay Lake starved, its nutrients declining to one-third of earlier levels. Food chains began to collapse, and by 1990 the Kokanee (non-sea-going Sockeye Salmon) population had declined precipitously. The big Bull Trout and Rainbow Trout that fed on the smaller Kokanee also suffered. Only after an extensive program of artificial fertilization of the lake was begun in 1992 did these fish begin to recover. Fertilization increased the plankton eaten by small fish, which in turn fed the larger fish.
