|Map Sheets||82 G/10|
|Lat / Long||49.6333333, -114.6333333|
|Max depth||27.4 m|
|Mean depth||13.5 m|
|Dr. Basin Area||85.6 km2|
|Drainage Basin||Oldman River Basin|
|Sport Fish||Lake Trout, Rainbow Trout, Cutthroat Trout, Mountain Whitefish|
|TP x||No Data µg/L|
|CHLORO x||No Data µg/L|
|TDS x||226 mg/L|
Crowsnest Lake is a deep, blue lake situated in narrow, windswept Crowsnest Pass in southern Alberta, just east of the Alberta-British Columbia boundary. To reach the lake from the city of Lethbridge, follow Highway 3 west for about 135 km to the town of Coleman then continue west for another 10 km to the south side of the lake (FIGURE 1). The lake is in the Municipality of Crowsnest Pass.
The origin of the name "Crowsnest" is unclear. It possibly arose following a battle when Blackfoot Indians cornered and defeated a group of Crow Indians, or it may refer to the sighting of a large crow's nest in the area; possibly, the lake was named for a mountain known to the Indians as Crow's Nest Mountain (Cousins 1981). The lake was called Old Man's Lake in the early days of settlement, and the Crowsnest River draining the lake was called the Middle Fork of the Oldman. The first white man through the pass was likely Father Jean de Smet in about 1845. Ten years later, the Palliser Expedition passed through the area.
A dam on the lake and flumes to the river were built in the early 1900s by Peter McLaren (the late Senator McLaren) to release water to float logs to his sawmill in Blairmore (Cousins 1981). This operation closed in 1920 and there is no longer a control structure on the lake. At the eastern end of the lake, the East Kootenay Power company operated a coal-fired power plant from 1927 to the mid-1950s, using locally mined coal. Strip mining for coal was carried out in the Crowsnest Creek drainage area from 1922 to 1929 and on nearby Tent Mountain from 1949 to 1955 and from 1969 to 1980 (FIGURE 1). Summit Lime Works extracts lime from quarries along the north shore of Island Lake and along Crowsnest Creek. The limestone is processed at a plant located between Crowsnest and Island lakes. The only residences near Crowsnest Lake are associated with the lime plant and there are almost no other residences in the drainage basin (Fitch 1978). Other developments near Crowsnest Lake include a motel and a church camp on its west shore. The Canadian Pacific Railway hugs the north shore and Highway 3 skirts the south shore.
There is no public campground on Crowsnest Lake; the nearest one is Island Lake Campground, 4 km west on Highway 3. This facility is operated by Alberta Transportation and Utilities and offers 35 campsites, picnic tables and shelters (Alta. Hotel Assoc. 1989). Boat access to Crowsnest Lake is available at a public boat launch at the east end of the lake. There are no boating restrictions for Crowsnest Lake but only battery-powered motors are permitted on adjoining Emerald Lake (Alta. For. Ld. Wild. 1988).
Crowsnest Lake is moderately popular for sport fishing for rainbow trout, mountain whitefish and lake trout. No fishing with bait fish is permitted in the region, including Crowsnest Lake. All flowing water is open to fishing only from 1 June through 31 October. A bait ban is in effect in flowing water except from 15 August to 31 October (Alta. For. Ld. Wild. 1989). The clear water and barren, weed-free shores make Crowsnest Lake attractive for swimming, but the low water temperature deters all but the hardiest swimmers.
Crowsnest Lake lies in a major mountain pass that cuts through the mountains that form the Continental Divide in southern Alberta. The pass separates two ranges, the northern High Rock Range and the southern Flathead Range (FIGURE 1). The highest peaks in the basin are Mount Tecumseh (2,550 m) to the north and Ptolemy Mountain (2,815 m) to the south. The drainage basin is bordered on three sides by the Alberta-British Columbia border. When the British Columbia border was established in the late nineteenth century, it was to follow the continental divide - all land in British Columbia was to drain to the Pacific Ocean and all land east of the border was to drain to the Atlantic or Arctic oceans. However, recent examination of the Crowsnest drainage basin shows that the official Alberta-British Columbia boundary strays in some places from the continental divide (Alta. Envir. n.d.[a]). Therefore, some land in Alberta actually drains to the Pacific Ocean, whereas some land in southern British Columbia drains to Hudson Bay.
The mountains and ridges surrounding Crowsnest Lake are formed of erosion-resistant Paleozoic limestone, whereas the lower ridges are formed of sandstone. The shape of the pass and the surficial deposits are a result of the last Cordilleran glaciation which flowed from the divide toward the plains to the east. This ice sheet deposited a heterogeneous mixture of stony and calcareous glacial till in lateral moraines along the mountain slopes. These moraines subsequently eroded and formed alluvial fans throughout the valley; the area between Island and Crowsnest lakes is an example of such a fan (Boyacioglu and van Waas 1975).
The Crowsnest Lake basin includes portions of three ecoregions: Montane, Subalpine and Alpine (TABLE 1). The Montane Ecoregion includes the south-facing slopes just north of the lake up to an elevation of approximately 1,500 m (Boyacioglu and van Waas 1975). On these coarse-textured, dry slopes, Douglas fir groves are interspersed with areas of grass and low shrubs; the soils are typically well-drained Eutric Brunisols. The valley floor supports white spruce and pine, and willow and birch grow in poorly drained areas. The Subalpine Ecoregion lies above the Montane Ecoregion and extends up to an elevation of about 2,135 m. Coniferous forests of lodgepole pine, Engelmann spruce and white spruce are generally present; they are underlain by Eutric Brunisolic soils. On well-drained south-facing slopes north of the Crowsnest Valley, areas of trembling aspen and fescue grasses grow on Chernozemic soils. Above the treeline is the Alpine Ecoregion (FIGURE 1), which supports only sparse vegetation that consists mostly of forbs, heaths, shrubby willow and dwarf birch, with patches of krumholz alpine fir and Engelmann spruce. Soils are Brunisols and Regosols (Strong and Leggat 1981).
A disjunct area that includes most of the shoreline of Crowsnest Lake, all of Emerald Lake and the south-facing slopes above the valley has been proposed as a natural area (Alta. For. Ld. Wild. 1987). This area has vegetation typical of the Montane Ecoregion: Douglas fir, limber pine and grassland. As of 1988, the area had Protective Notation status.
The major inflow to Crowsnest Lake is Crowsnest Creek, which flows northward from the slopes of Tent and Ptolemy mountains. It is joined by the outflow from Island Lake, then enters the west end of Crowsnest Lake. Emerald Lake, which receives runoff from Sentry Mountain, also flows into Crowsnest Lake. The only other tributary of any significance is a stream formed by springs in a cave on the north shore; additional groundwater inflow is also likely important in the lake. The outflow from the lake is the Crowsnest River, a major tributary of the Oldman River.
Crowsnest Lake is long (3.9 km) and narrow (maximum width of 0.7 km), with three deep basins connected by slightly shallower shelves (FIGURE 2). The lake basin drops steeply on most sides to a maximum depth of 27.4 m (TABLE 2). Areas shallower than 3 m constitute only 15% of the area of the lake (FIGURE 3) and are located mostly at the east end of the lake and in a small area on the north shore.
The shoreline is composed of bedrock outcrops, large boulders and gravel. The substrate is mostly gravel and fractured shale in the littoral zone; deeper areas have a silt substrate. Near the inlet, divers report a whitish-gray deposit, which probably originated from the lime works, and in the western portion of the lake coal particles are common (Fitch 1978). The residence time of water in the lake is estimated to be 0.6 years (Alta. Envir. n.d.[a]). The lake level has not been monitored and there is no information on its fluctuations.
Some components of the water quality of Crowsnest Lake were sampled by Fish and Wildlife Division on six occasions during the open-water season of 1976 (Fitch 1978).
Crowsnest is a freshwater lake (TABLE 3). In 1976, the temperature and dissolved oxygen concentrations at the top and the bottom of the water column, as well as the Secchi depth, were measured monthly from late April to mid-October (Fitch 1978). Weak thermal stratification was apparent from early July until late August (surface maximum 13.5°C; bottom maximum 10°C). The dissolved oxygen concentration at the surface ranged between 9 and 11 mg/L throughout the summer; in the bottom water, it dropped from 10 mg/L in early June to 7 mg/L in late July. The Secchi depth varied from 1.9 to 4.2 m; turbidity was attributed to silt suspended by wind and to runoff from the lime plant. Under-ice dissolved oxygen concentrations were monitored on 8 January 1981 at a site where the lake was 17-m deep. The concentration of dissolved oxygen dropped from 13 mg/L at the surface to 8 mg/L on the bottom (Alta. For. Ld. Wild. n.d.).
There are no data on nutrients or chlorophyll a concentrations in Crowsnest Lake, so it is difficult to determine the lake's trophic status. The lack of aquatic vegetation, the apparent sparseness of algae, the dominance of diatoms, the high dissolved oxygen concentrations and the low temperatures indicate that the lake is likely oligotrophic.
The phytoplankton was sampled monthly from April to October in 1976 during a Fish and Wildlife Division study; however, since the net was made of number 20 mesh silk bolting cloth, the small algae were probably missed (Fitch 1978). A total of 25 species were identified. Diatoms (Bacillariophyta) were dominant in every sample; in descending order, the most abundant diatom genera were Asterionella, Melosira, Fragilaria, Stephanodiscus and Tabellaria. Golden-brown algae (Chrysophyta) were sparse in most samples; Dinobryon divergens was the most abundant species. Only one species of green algae (Chlorophyta), Pediastrum sp., was found, and then only in early spring and late autumn.
Aquatic macrophytes are very sparse in Crowsnest Lake; the rocky shore and strong wave action inhibit growth along most of the shoreline.
The zooplankton was sampled monthly from April through October in 1976 with a net of number 20 mesh silk bolting cloth (Fitch 1978). Twelve species were collected. Rotifers, primarily Keratella cochlearis, dominated throughout the sampling period and Polyarthra (vulgaris?), Asplanchna (priodonta?) and Synchaeta (oblonga?) were fairly abundant. Copepods, mostly Diacyclops bicuspidatus thomasi, were the next most numerous group. Cladocerans formed only a minor component of the zooplankton; Bosmina longirostris was the most abundant species.
In 1973, approximately 75,000 opossum shrimp (Mysidacea: Mysis relicta) from Kootenay Lake, British Columbia, were released into Crowsnest Lake to augment the food supply for trout (Alta. For. Ld. Wild. n.d.). None were caught in plankton tows in 1976 (Fitch 1978) and none have been seen in the stomach contents of fish caught to date (Fitch 1989).
Benthic invertebrates have not been comprehensively surveyed.
Six species of fish are known to inhabit the Crowsnest Lake area. Indigenous species include mountain whitefish and Iongnose suckers; forage species have not been documented (Alta. For. Ld. Wild. n.d.). Rainbow trout are likely indigenous, but they were also stocked in most years from 1926 to 1970 and from 1977 to 1979 in Crowsnest and/or Island lake. Cutthroat trout were planted in either Crowsnest or closely connected Island and Emerald lakes almost annually from 1974 to 1987. As well, an average of 8,500 lake trout were planted annually in Crowsnest Lake from 1977 to 1983 and in 1986 and 1987. Adult brook trout were introduced to Emerald and Island lakes in 1988 (Alta. Ld. For. 1949-1974; Alta. Rec. Parks Wild. 1975-1978; Alta. En. Nat. Resour. 1979-1985; Alta. For. Ld. Wild. 1986-1988).
Despite the intensive fish-stocking program, the sport fishery is poor in Emerald Lake and only sporadically good in Island Lake. Sport fishing for lake trout is moderate in Crowsnest Lake; anglers report catching fish that weigh up to 5 kg (Bishop 1989). Lake trout have also been caught in the Crowsnest River as far downstream as Lundbreck Falls (Fitch 1989). Test netting was carried out in late June and early July in 1986 in Crowsnest, Island and Emerald lakes (Alta. For. Ld. Wild. n.d.). Of the 111 fish caught in Crowsnest Lake, 61 were mountain whitefish, 16% were rainbow trout, 13% were long-nose suckers, 7% were lake trout, and 3% were cutthroat trout. In Island Lake, the proportion of longnose suckers caught increased from 5% in 1975 to 30% in 1979 and to 58% in 1986. Of the 1986 catch (total of 103 fish), 22% were mountain whitefish and 20% were cutthroat or brook trout. In Emerald Lake, only three fish were caught-two mountain whitefish and one cutthroat trout. The 1986 test netting indicated that lake trout in Crowsnest Lake grow very slowly to age five, then rapidly after age five. This is likely due to a shift in prey from midge larvae to mountain whitefish.
Crowsnest Lake does not provide good waterfowl habitat because of its rocky, wave-washed shore. Common Mergansers, Canada Geese and Mallards occasionally visit the lake (Fitch 1989).
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-----. n.d.[b]. Tech. Serv. Div., Surv. Br. Unpubl. data, Edmonton.
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Alberta Recreation, Parks and Wildlife. 1975-1978. Fish planting list. Fish Wild. Div., Edmonton.
Alberta Research Council. 1972. Geological map of Alberta. Nat. Resour. Div., Alta. Geol. Surv., Edmonton.
Bishop, F. 1989. Alta. For. Ld. Wild., Fish Wild. Div., Lethbridge. Pers. comm.
Boyacioglu, E. and C. van Waas. 1975. Biophysical analysis and evaluation of capability, Crowsnest Pass. Alta. En. Nat. Resour., Tech. Div., Edmonton.
Cousins, W.1. 1981. A history of Crow's Nest Pass. The Hist. Trails Soc. Alta., Lethbridge.
Energy, Mines and Resources Canada. 1973. National topographic series 1:50 000 82G/10 (1973). Surv. Map. Br., Ottawa.
Environment Canada. 1982. Canadian climate normals, Vol. 7: Bright sunshine (1951-1980). Prep. by Atm. Envir. Serv. Supply Serv. Can., Ottawa.
Fitch, L. 1978. A limnological survey of Crowsnest Lake. Alta. Rec. Parks Wild., Fish Wild. Div., Lethbridge.
-----. 1989. Alta. For. Ld. Wild., Fish Wild. Div., Lethbridge. Pers. comm
Strong, W.L. and K.R. Leggat. 1981. Ecoregions of Alberta. Alta. En. Nat. Resour., Resour. Eval. Plan. Div., Edmonton.