McGregor Lake

The contents of this online version has not been altered or modified from the original 1990 publication. It is reasonable to assume that much of the data e.g. water levels, camp grounds/boat launches, etc. is out of date. For updated or additional information on any of the lakes in this atlas please go to Environment Alberta's water web site.

Basic Info
Map Sheets82I
Lat / Long50.4000000, -112.8333333
50°23'N, 112°49'W
Area51.4 km2
Max depth9.7 m
Mean depth6.5 m
Dr. Basin Area993 km2
Dam, WeirDam
Drainage BasinOldman River Basin
Camp GroundNone
Boat LaunchPresent
Sport FishWalleye, Yellow Perch, Lake Whitefish, Rainbow Trout, Northern Pike
Trophic StatusMesotrophic?
TP x26 µg/L
CHLORO x8.8 µg/L
TDS x195 mg/L
Photo credit: unknown


McGregor Lake is an offstream storage reservoir created in 1920 by the completion of two dams bracketing Snake Lake in Snake Valley. It is situated 30 km east of the town of Vulcan in the County of Vulcan. McGregor Lake, Travers Reservoir and Little Bow Lake Reservoir are all part of the Carseland-Bow River Headworks System that is owned and operated by Alberta Environment and delivers water to the Bow River Irrigation District (BRID) (inset, FIGURE 1). McGregor Lake is in the Oldman River drainage basin, but almost all the water in it is derived via diversion from the Bow River near the hamlet of Carseland.

For centuries, the Snake Valley was a major thoroughfare for members of the Blackfoot Confederacy (Milo Dist. Hist. Soc. 1973). By the 1880s, British and European settlers had arrived and ranching was well established; homesteading and cultivation began soon after the turn of the century (IEC Beak Consult. Ltd. et al. 1983). The combination of rich soil and dry climate soon led to an interest in irrigation, and McGregor Lake was one of the first developments to meet this need.

McGregor Lake was created when the British-owned Canada Land and Irrigation Company built the South and North McGregor dams and a canal to bring water from the Bow River near Carseland. The reservoir was named after J.D. McGregor, the company's Canadian manager who became Lieutenant-Governor of Manitoba in 1929 (Holmgren and Holmgren 1976). Construction of the dams started in 1909; the outlet works were completed in 1919 and reservoir filling began in 1920 (Walk and Hurndall 1978[a]; 1978[b]). In 1950, the federal Prairie Farm Rehabilitation Administration assumed control. From 1952 to 1954, the original homogeneous earthfill South Dam was modified to a zoned earthfill dam (Walk and Hurndall 1978[b]). In 1973, McGregor Lake and its control structures were transferred to Alberta Environment.

The population centre closest to the lake is the village of Milo (population 117 in 1986), located about 2 km to the northeast (FIGURE 1). The land up to the full supply level of the reservoir is Crown land; the Crown also owns about 30% of the land above the full supply level and most of it is leased for grazing (FIGURE 2). There are no cottage developments and very few recreational facilities on the lake. The best access is at McGregor Lake Recreation Area (formerly Milo Campground), an Alberta Environment day-use site at the northwest corner of the lake (FIGURE 2). Facilities include a boat launch, a playground, a baseball diamond and two picnic shelters. Small boats can also be launched at Lomond Crossing, where Secondary Road 531 crosses the lake.

McGregor Lake has attractive, clear water. Algal concentrations are usually low and do not interfere with recreational use. Activities enjoyed at the lake include picnicking, swimming, fishing, wind surfing, canoeing, water skiing and power boating. Federal boating regulations apply but there are no restrictions specific to the reservoir (Alta. For. Ld. Wild. 1988). However, boaters should be aware of the strong prevailing winds from the west and southwest that can cause high waves (Richard Strong Assoc. Ltd. 1983). The lake supports a substantial commercial fishery for lake whitefish and a sport fishery for northern pike, lake whitefish and rainbow trout. Provincial sport fishing limits and regulations apply to McGregor Lake. The inflowing canal from the Bow River between Secondary Road 542 and the reservoir is closed to fishing from 1 September to 30 November (Alta. For. Ld. Wild. 1989).

Drainage Basin Characteristics

The natural watershed of McGregor Lake is 993 km2 (TABLE 1). The topography of the land varies from generally flat in the north to hummocky and rolling toward the south and southwest (Richard Strong Assoc. Ltd. 1983). The lake is located in a valley that formed as a glacial outwash channel after the last ice-age. The sides of the valley are dissected by coulees.

The basin lies within the Mixed Grass Ecoregion (Strong and Leggat 1981). Natural vegetation in the region consists of short grasses, bunch grasses and long grasses. Woody plants such as trembling aspen, balsam poplar, eastern cottonwood, willow and other shrubs grow in valleys and coulees where more moisture is available than on the arid plain (Richard Strong Assoc. Ltd. 1983). Much of the natural vegetation in the basin has been replaced by cereal crops. Soils are mostly Orthic Dark Brown Chernozemics (Wyatt and Newton 1925; Wyatt et al. 1960; Greenlee 1974).

Cattle grazing and dryland farming of crops such as wheat, barley, hay, canola and rye are the dominant agricultural land uses (IEC Beak Consult. Ltd. et al. 1983). There is a gas processing plant near the south end of the drainage basin, and a large number of cattle and swine feedlots, and several oil, gas and coal fields in the area. The town of Vulcan is located on the western border of the watershed (FIGURE 1).

A few small permanent and intermittent streams enter McGregor Lake, but most of the inflow (97%) comes from the Bow River near Carseland via 64 km of canal. This water enters the north end of the reservoir, flows through four culverts at Lomond Crossing, and leaves through an outlet structure in the dam at the south end. From 1920 to 1954, water flowed out of McGregor Lake through 20 km of canal directly to Little Bow Lake Reservoir. In 1954, Travers Reservoir was built to replace most of this canal; now, water from McGregor Lake flows through the McGregor-Travers Canal to Travers Reservoir, then to Little Bow Lake Reservoir, and then to the Bow River Irrigation District to supply water for irrigation and to support multi-purpose water use.

Lake Basin Characteristics

The shore around McGregor Lake varies from hills at the south end, to steep, eroded perpendicular banks in the middle section, to flatlands at the north end (Wyatt and Newton 1925; Wyatt et al. 1960). The bottom sediments range from sandy clay to silt and clay; an artificial beach of sand and gravel has been built at the recreation area at the north end of the lake.

The reservoir was built with a design full supply level of 874.38 m, but the operating full supply level has not exceeded 873.77 m (Alta. Envir. n.d.[a]). The reservoir bottom slopes steeply to a maximum depth of 9.7 m (TABLE 2, FIGURE 2). The mean depth at the operating full supply level is 6.5 m. The reservoir first reached the operating full supply level in 1971. Since then, the surface elevation of the lake during the open-water season has fluctuated between a low of 869.8 m in 1977 and the operating full supply level in 1985 (FIGURE 3). Annual fluctuations averaged 2.0 m from 1975 to 1987, but in three years during this period the annual fluctuation exceeded 3.0 m. The lake level stays almost constant from November to May. Typical annual fluctuations are shown in Figure 4; the reservoir is filled in the fall and the level is held steady through the winter, then water is withdrawn throughout the summer to meet demand for water. When the reservoir is drawn down to 2 m below the operating full supply level, the surface area is reduced by 20% (FIGURE 5).

The main inflow via the Carseland-Bow River Headworks Canal is usually restricted to the period between late April and early November. The reservoir volume is usually exchanged at least once every summer; virtually no inflow or outflow occurs from November to late April.

Water Quality

McGregor Lake was sampled in 1983 and 1984 by Alberta Environment (Alta. Envir. n.d.[b]). It is a freshwater lake (total dissolved solids average 185 mg/L, TABLE 3) dominated by bicarbonate, sulphate and calcium ions. The ionic composition of the lake is similar to that of its main source, the Bow River.

In 1984, the central region of McGregor Lake was only very weakly thermally stratified between May and mid-August (FIGURE 6). The level of dissolved oxygen at this location declined to less than 5 mg/L near the bottom during late July, but the lake generally remained well-oxygenated throughout the ice-free season (FIGURE 7).

Phosphorus levels in the Bow River were reduced after phosphorus removal was initiated at the Calgary sewage treatment plant in the winter of 1982/83 (Charlton and Bayne 1986). Average total phosphorus values in the Bow River at Carseland decreased from 178 µg/L in 1980 to 40 µg/L in 1983. McGregor Lake receives almost all of its inflow from the Bow River, so the reduced phosphorus loading may result in long-term improvement in the reservoir's water quality. Mean total phosphorus levels in the lake declined from 30 µg/L in 1983 to 22 µg/L in 1984 (TABLE 4). Relatively high nitrite plus nitrate values also originate from the large proportion of water diverted from the Bow River downstream of Calgary. Approximately 50% of nitrogen is removed by sewage treatment.

The peak chlorophyll a value in 1984 (FIGURE 8) suggests that, at that time, McGregor Lake was mesotrophic; however, because no recent water quality data are available, the lake's present trophic status cannot be determined.

Biological Characteristics


There is no detailed information available on the algae in McGregor Lake. During a survey conducted in 1981 (English 1985), the total plankton biomass (settled volume) peaked in July and was dominated at that time by the dinoflagellate (Pyrrhophyta) Ceratium sp.

Macrophytes have not been examined, but weedy areas have been reported in the shallow northern end of the lake (Alta. For. Ld. Wild. n.d.).


Zooplankton abundance was measured during a survey in 1981 (English 1985). At the north end of the reservoir, a higher mean density of zooplankton (237/L) and a greater mean settled volume of plankton (0.023 mL/L) was accompanied by a lower transparency (mean Secchi depth of 1.6 m) than at the south end, where mean density was 176/L, mean settled volume was 0.018 mL/L and Secchi depth was 2.3 m. The number of Cladocera in the lake was low and the zooplankton community was dominated by Copepoda and Rotifera; the latter group increased sharply in abundance during September.

The numbers, biomass and composition of benthic invertebrates were also briefly studied in 1981 (TABLE 5). In May and July, midge larvae (Chironomidae) were dominant at both ends of the reservoir.


Nine species of fish have been observed in McGregor Lake. Lake whitefish probably were introduced first in 1938 (English 1985). Walleye were introduced as eyed-eggs in 1938, 1949 and 1951 but only a small number are taken each year. Yellow perch likely were introduced between 1938 and 1950, since they were stocked in many Alberta lakes at that time. There are no records of fish having been stocked since 1972 (Alta. For. Ld. Wild. n.d.). Other species that have migrated into the lake via the canal from the Bow River include rainbow trout, northern pike, spottail shiner, longnose sucker, white sucker and burbot. Fish movement is unrestricted throughout the Bow River irrigation system between spring (April or May) and fall (October or November) when the canals are open. During the winter, however, fish are restricted to the reservoirs.

McGregor Lake supports a sport fishery for northern pike, lake whitefish and rainbow trout (Richard Strong Assoc. Ltd. 1983; R.L. & L. Envir. Serv. Ltd. 1985). The lake is heavily fished in summer and in winter. A creel survey was conducted in 1982 at the North Dam and near the mouth of the inflowing canal (Bishop 1983). At the North Dam between May and August, the catch per unit effort was 0.42 pike/angler-hour; no trout were captured. At the canal mouth between May and October, the catch per unit effort was 0.28 pike/angler-hour and 0.08 trout/angler-hour; lake whitefish were captured during October at this site, as well. Illegal snagging was common.

McGregor Lake has been fished commercially for lake whitefish since about 1948 (Alta. For. Ld. Wild. n.d.). Before 1938, the lake was fished commercially for northern pike. Between the 1980/81 and the 1987/88 seasons, the mean annual commercial catch was 85,230 kg of lake whitefish and 734 kg of northern pike-a total annual average of 85,964 kg of fish. The reservoir was closed to commercial fishing between 1974 and 1978 to allow recovery of the lake whitefish population after an extreme drawdown was followed by a year-class failure in 1972/73. This drawdown resulted from closure of the Carseland-Bow River Headworks Canal when the Bow River diversion structure at Carseland was rebuilt. In 1978, Fish and Wildlife Division biologists determined the size-at-age and maturity of lake whitefish caught in the McGregor Lake commercial fishery (English 1985). Most of the age four fish were immature, whereas most of the age five fish were mature.

During the late 1950s and early 1960s, there were reports of particularly lean lake whitefish caught by the commercial fishery in McGregor Lake (Alta. For. Ld. Wild. n.d.; Hartman 1957). A 1957 investigation of the invertebrate community on the lake bottom suggested that the north end produced fewer of the prey preferred by lake whitefish than did the south end. The low production at the north end may be due to heavy silt loads deposited by inflowing water during the summer (Hartman 1957). A 1981 study of benthic invertebrates, however, found no difference between the north and south ends of the lake (English 1985).

By 1985, lake whitefish in McGregor Lake were again reported to be lean and continued to be so in 1988. The cause appeared to be a parasite, Diphyllobothrium dendriticum, which lives in the intestines of the host lake whitefish. Parasite populations tend to be cyclic and the fish population is expected to be healthier in a few years (Bishop 1988). Even with parasites, the lake whitefish are safe to eat if cleaned and thoroughly cooked.

A 1982 investigation of pesticide and PCB levels in McGregor Lake fish found that concentrations were low and well below safe consumption limits (Alta. Envir. 1982).


McGregor Lake is used as a staging area by waterfowl during migration (IEC Beak Consult. Ltd. et al. 1983; Richard Strong Assoc. Ltd. 1983). The north end of the lake, the slough north of the North Dam, and Snake Creek are important nesting areas for ducks. Gulls use the lake, especially the north end, for resting at night and for staging (Fitch 1988).

J.M. Crosby


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