|Lat / Long||54.3000000, -115.6500000|
|Max depth||10.7 m|
|Mean depth||5.1 m|
|Dr. Basin Area||45.9 km2|
|Drainage Basin||Athabasca River Basin|
|Sport Fish||Rainbow Trout|
|TP x||26 µg/L|
|CHLORO x||9.3 µg/L|
|TDS x||165 mg/L|
McLeod Lake is a medium-sized lake set in gently rolling, forested land in Carson-Pegasus Provincial Park. The lake is located 200 km northwest of the city of Edmonton and 24 km north of the town of Whitecourt. It is valued for its excellent rainbow trout fishery, which is the central attraction for visitors to the park. The park itself is one of the more popular parks in Alberta. To reach the lake from Whitecourt, drive west for 9 km on Highway 43 and north for 10 km on Highway 32. Turn east onto the road that leads to the park and drive for about 5 km to the park entrance (FIGURE 1).
There is some uncertainty about the origin of the lake's name. The McLeod River, which joins the Athabasca River at Whitecourt, was probably named for Archibald Norman McLeod, a fur trader with the North West Company (MacGregor 1952). In 1790, McLeod was sent by Alexander Mackenzie to build two trading posts near the present-day town of Peace River, 250 km northwest of Whitecourt. In the early days of the fur trade, McLeod Lake was an important stop for travellers who were using an intricate system of rivers and trails to reach northwestern Alberta (Finlay and Finlay 1987). At some point, the lake was renamed Carson Lake, but the name was changed back to McLeod Lake in the mid-1980s. Nearby Little McLeod Lake was formerly known as Pegasus Lake, probably in reference to the Pegasus symbol that was at one time used by Mobil Oil of Canada Limited, which leases much of the land in the drainage basin.
Several significant prehistoric sites are located in the provincial park. Stoney, Woodland Cree, and possibly Beaver Indians lived near the lake until the early part of the twentieth century (Finlay and Finlay 1987). The lake was an important source of fish for these people. The first white settler, Bruce Goodwin, was a timber "cruiser" for the federal government who settled at McLeod Lake in 1904. The lumber industry began in the area in the early 1900s, and most of the park was selectively logged during the 1940s (Olecko 1974; Finlay and Finlay 1987). In 1956, oil was discovered in the region, and since then, many roads and cutlines have been developed.
Carson-Pegasus Provincial Park was established by the provincial government in 1982. Prior to that date, the Alberta Forest Service had operated a campground at the lake. The park was named for Carson (now McLeod) and Pegasus (now Little McLeod) lakes, both of which lie within its boundaries (FIGURE 1). It is open year-round and provides 182 campsites, a group camping area, showers, tap water, a concession, sewage disposal facilities, playgrounds, a picnic area, boat launches and rentals and walking trails. All of the facilities are located on the south shore of McLeod Lake and along the peninsula (FIGURE 2); a road and hiking trail provide access to Little McLeod Lake.
The water in McLeod Lake is generally transparent, but may turn green in late summer. Bulrushes and sedges ring the lake and two shallow shoals support dense stands of aquatic vegetation. Popular activities at Carson-Pegasus Provincial Park are fishing for rainbow trout, hiking, camping and motor boating in summer, and camping, ice fishing, cross-country skiing, snowshoeing and tobogganing in winter. Little McLeod Lake is good for swimming, but in McLeod Lake, large numbers of leeches are a deterrent to swimmers. All tributary streams to McLeod Lake, and the outlet stream as far downstream as Highway 32, are closed to fishing year-round (Alta. For. Ld. Wild. 1989). As well, fishing for bait and the use of bait fish are not allowed in the lake. Power boats are limited to a maximum speed of 12 km/hour in all areas of the lake, and all boats are prohibited from posted areas of the lake (Alta. For. Ld. Wild. 1988).
Most of McLeod Lake's drainage basin is situated north of the lake (FIGURE 1). The watershed, which covers almost 46 km2, is about 12 times larger than the lake (Tables 1, 2). The main inflow is an unnamed creek that flows into the north end of the lake. A small creek flows from nearby Little McLeod Lake into the eastern side of McLeod Lake. McLeod Lake's outlet is located on the western shore. It flows into Carson Creek, which joins the Sakwatamau River on its way to the Athabasca River.
Land in the drainage basin is generally undulating to rolling (Wynnyk et al. 1969). The highest land elevation, 1,067 m, is at the far northern tip of the watershed, where the topography is hilly. Elevations decline to about 854 m near the shore of McLeod Lake.
The drainage basin is part of the Boreal Foothills Ecoregion (Strong and Leggat 1981). Soils are mainly moderately well-drained Orthic Gray Luvisols that developed primarily on glacial till and secondarily on shale. Most of the soils north of the lake are rated as suitable for pasture and woodland. Around the shore the soil arability rating varies from poor to fairly good (Wynnyk et al. 1969). Trembling aspen, balsam poplar and lodgepole pine are the codominant trees on well-drained to moderately well-drained Gray Luvisols. Succession on these soils is by white spruce. Open stands of lodgepole pine grow on well-drained Brunisols and imperfectly drained Gleysols, and black spruce is the main species on poorly drained, depressional areas. Willows and sedges grow in very poorly drained areas.
The major land uses in the watershed are recreational and industrial. There is no residential or agricultural development. Recreational developments are located on the south shore of McLeod Lake within the provincial park (FIGURE 1). All of the land in the watershed belongs to the province, and much of it is leased to either Mobil Oil of Canada Limited or, secondarily, to Esso Resources Canada Limited. Mobil Oil is licenced to withdraw water from Little McLeod Lake, whereas Esso Resources is licenced to withdraw water from McLeod Lake.
McLeod Lake is a shallow, medium-sized water body that is divided into two basins by a long peninsula (TABLE 2, FIGURE 2). The east basin, which is deepest, has a maximum depth of 10.7 m, located in the central area. The deepest area in the west basin (6.1 m) is located near the tip of the peninsula. Most of the bottom substrate is highly organic, but there are small areas of sand, clay, rubble, and mixtures of these substrates, as well (Crutchfield and Lane 1971).
The elevation of McLeod Lake was recorded once in 1962 and has been monitored continuously since 1966 (FIGURE 3). In September 1962, a water level of 853.06 m was recorded. Similar elevations were recorded in 1966, but after that time, the lake level declined quite steadily to its historic minimum elevation of 851.05 m in May 1971. This decline was attributed to several years of low precipitation levels. Imperial Oil Company (now Esso Resources Canada Limited) was first licenced in September 1962 to withdraw 3.08 x 106 m3/year of water from McLeod Lake (Alta. Envir. n.d.[d]). The licence was increased to 3.58 x 106 m3/year soon after. In November 1968, Imperial Oil built a temporary earthfill weir on the outlet creek.
In 1971, Imperial Oil changed their primary water source from McLeod Lake to the Athabasca River because the water supply from McLeod Lake was not reliable. They constructed a pipeline from the river to the south shore of McLeod Lake to bring water into the lake and raise its elevation. They then pumped water out of the lake from a station on the north shore. In effect, they used the lake as a balancing reservoir. In July 1971, a permanent sheet-pile weir with an elevation of 853.74 m was built on the outlet of McLeod Lake and the company began filling the lake with river water. By mid-July, the lake's elevation had risen by 1.90 m, from the historic minimum of 851.05 m on 17 May to 852.95 m on 14 July (FIGURE 3). The company was issued a new withdrawal licence in 1971 for a total of 13.44 x 106 m3 of water per year, to be taken from both the lake and river, and the company was not allowed to draw the lake down below 852.68 m (Alta. Envir. n.d.[d]).
From 1972 to 1979, Imperial Oil withdrew an average of 8.21 x 106 m3/year from the two water sources. Since 1980, the company's water needs have declined and they have not pumped water from the Athabasca River, although they are still licenced to do so. From 1980 to 1988, the company withdrew an average of 2.09 x 106 m3/year, from the lake only (Alta. Envir. n.d.[d]).
During the 1980s, water levels were quite high in most years (FIGURE 3). The historic maximum level, 854.37 m, was recorded in July 1985. These high levels were caused by beaver dams built on and around the control structure. The high water levels caused flooding problems in the provincial park, and Fish and Wildlife Division became concerned that northern pike and white suckers, which had been eliminated from the lake in 1976, might overcome the fish barrier on the outlet, reenter the lake and adversely affect the stocked rainbow trout population. Consequently, a new weir, designed as a fish barrier, was installed in 1987. The project was a joint effort between Esso Resources, Fish and Wildlife Division, Alberta Recreation and Parks and Alberta Environment. The structure is licenced to Esso and is maintained by Fish and Wildlife Division. It is a sheet-pile weir with a crest elevation of 853.74 m, and is located downstream from the old weir, which was removed. To improve outflow, the stream was straightened and excavated, and to discourage beaver dam construction, trees near the channel were removed (Bucharski 1989).
Over the years, the area and capacity of McLeod Lake have fluctuated considerably. The difference between the historic maximum and minimum lake elevation is 3.32 m. This fluctuation would cause large changes in the lake's area and volume (FIGURE 4).
The water quality of McLeod Lake was monitored by Alberta Environment in 1976 and 1977, and jointly by Alberta Environment and Alberta Recreation and Parks since 1984 (Alta. Envir. n.d.[a]).
The major ions in the east and west basins of the lake are very similar (TABLE 3). The water is fresh, relatively hard and well-buffered, and the dominant ions are bicarbonate and calcium. Both basins are quite shallow and generally well mixed throughout the open-water season. The water column is weakly thermally stratified during warm, calm periods, such as on 21 July 1986 (FIGURE 5). On this date, dissolved oxygen concentrations declined to less than 5 mg/L below a depth of 9 m in the deeper east basin, and to about 6 mg/L in water near the sediments in the west basin (FIGURE 5). Surface concentrations were 9 to 10 mg/L in both basins. In the east basin during August of 1984 and 1985, dissolved oxygen concentrations were less than 1 mg/L at depths greater than 8 m. Data for dissolved oxygen levels in the west basin are not available for these dates.
In late winter, dissolved oxygen concentrations near the bottom sediments become slightly depleted in both basins. In March 1986, they declined to 2 mg/L near the bottom of the east basin and 5 mg/L near the bottom of the west basin (FIGURE 5). Although a severe fish kill occurred during the winter of 1970/71, dissolved oxygen levels appear to be adequate for fish survival during most winters. The 1970/71 kill was the result of low water levels and therefore insufficient dissolved oxygen (Hildebrand 1976).
McLeod Lake is mesotrophic. Patterns of total phosphorus and chlorophyll a concentrations during the open-water period are similar for both basins and fairly typical of many Alberta lakes: concentrations are lowest in June and July and peak in spring and late summer (FIGURE 6). The late summer peak is probably caused by internal loading of total phosphorus from the sediments to the surface water. In 1986, the maximum chlorophyll a concentration recorded in late August was 13.1 µg/L in the west basin and 14.5 µg/L in the east basin. The average total phosphorus concentration in 1986 was 26 µg/L in both basins, and the average chlorophyll a concentration was 7.7 µg/L in the west basin and 10.9 µg/L in the east basin (TABLE 4).
The phytoplankton and macrophyte communities in McLeod Lake have not been studied in detail. Fish and Wildlife Division reported a bloom of blue-green algae, mostly Aphanizomenon sp. in June and August 1970 (Crutchfield and Lane 1971). Phytoplankton species and abundance were studied by Alberta Environment in late 1976 and during 1977 but, as this was after the lake was treated with rotenone to remove northern pike and suckers in September 1976, the data could not be considered representative (Alta. Envir. n.d.[a]).
A preliminary survey conducted by Fish and Wildlife Division in 1975 found that emergent vegetation, primarily common great bulrush (Scirpus validus) and sedges (Carex sp.), ring the lake (Hildebrand 1976). Unidentified submergent species and yellow water lily (Nuphar variegatum) were abundant, particularly in the shallow northwest bay.
The zooplankton and benthic invertebrate communities of McLeod Lake have not been studied, but the lake is known for its large population of leeches.
McLeod Lake is managed as a recreational fishery. The fishery and its rehabilitation have been studied intensively by Fish and Wildlife Division since 1970 (Crutchfield and Lane 1971; Hildebrand 1976; Makowecki et al. 1978; Hunt 1986; Hildebrandt 1987; Hawryluk 1989). Prior to 1970, the fish fauna consisted of lake whitefish, northern pike, white sucker and burbot. No forage fish were caught in seine netting in 1970, but finescale dace were found in a nearby slough and in the creek joining the slough to McLeod Lake. In 1970, the lake was stocked with 250,000 walleye fry and 1,180 walleye adults. A severe winterkill in 1970/71 killed all of the walleye and whitefish. From 1971 to 1974, the lake was stocked with 100,000 to 300,000 fingerling rainbow trout each year. From 1972 to 1975, trout fishing was reported to be excellent, and in 1975, a provincial record was set when a trout weighing 7.4 kg was taken. In 1974, test-nets caught a large number of northern pike that apparently had preyed heavily on small rainbow trout. Trout stocking was discontinued that year, and plans were made to rehabilitate the lake by treating it with rotenone to remove all fish and then to restock it with rainbow trout.
In 1976, the chemical treatment of McLeod Lake, a nearby slough, all inlet streams and the outlet stream as far as Highway 32 was carried out. Prior to the treatment, fish barriers were constructed on the outlets of Little McLeod Lake, McLeod Lake and the slough to prevent the movement of northern pike and suckers in and out of McLeod Lake. After the rehabilitation was completed, rainbow trout were stocked at a rate of 1,200 fish/ha in 1977 and 1978 and about 600 fish/ha from 1979 to 1983. In 1984, the stocking rate was increased to about 1,200 fish/ha to compensate for heavy fishing pressure. Test-netting conducted from 1977 to 1986 indicated that northern pike were eliminated from the lake but white suckers were still present. White suckers were also caught by anglers in 1988. The trout fishery in McLeod Lake can be sustained only by stocking because there is no suitable spawning habitat available. Consequently, natural reproduction is very low.
The growth rate of rainbow trout in McLeod Lake is among the fastest of trout planted in 10 other lakes in the Edson region. From 1980 to 1984 in McLeod Lake, the average spring weight of 2-year-old trout was 0.53 kg and the average 3-year-old weighed 0.79 kg (Hildebrandt 1987). In 8 of the other 10 stocked lakes sampled in the region, the weight of the average 2-year-old rainbow trout ranged from 0.14 kg (Mary Gregg Lake, 1976) to 1.48 kg (Grande Cache Lake, 1984). This age-class was not observed in the other two lakes. In 5 of the 10 lakes, the weight of the average 3-year-old trout ranged from 0.25 kg (Middle Pierre Grey Lake, 1981) to a single fish of 1.65 kg (Petite Lake, 1984).
Since 1977, limited creel censuses have been conducted frequently at McLeod Lake. In February and March 1988, a total of 625 anglers were interviewed on 12 census days. The anglers spent 2,436 hours fishing and caught 1365 rainbow trout. This catch rate (0.56 trout/angler-hour) is above the provincial average of 0.50 trout/angler-hour (Hawryluk 1989).
Carson-Pegasus Provincial Park is located near the Swan Hills and is home to both foothill and boreal bird species. The park is covered by young-mature and over-mature forests, marshes, fens and adjacent thickets. At least 113 species of birds have been reported, with 106 breeding in the park. Each year, the lake is used by waterfowl during spring and fall migration. The mammal population is diverse, with 42 species reported. Moose, deer and black bears are common, and the Swan Hills grizzly, a prairie subspecies, is present in the general area, but not common (Alta. Rec. Parks 1980; Nordstrom 1980).
M.E. Bradford and J.M. Hanson
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