Ethel Lake

Basic Info
Map Sheets73L/9
Lat / Long54.5333333, -110.3500000
54°31'N, 110°20'W
Area4.90 km2
Max depth30 m
Mean depth6.6 m
Dr. Basin Area542 km2
Dam, WeirWeir
Drainage BasinBeaver River Basin
Camp GroundPresent
Boat LaunchPresent
Sport FishWalleye, Yellow Perch, Northern Pike, Lake Whitefish
Trophic StatusMesotrophic
TP x25 µg/L
CHLORO x8.0 µg/L
TDS x172 mg/L
Photo credit: unknown


Ethel Lake is an attractive, peaceful lake set in low, rolling hills. It is located about 18 km northwest of the town of Cold Lake and 295 km northeast of the city of Edmonton near the southern boundary of improvement District No. 18. It can be reached by two improved roads that branch north from Highway 55. These roads, locally known as Ethel Lake Road and Primrose Lake Road (FIGURE 1), are joined by an east-west road at the north end of Ethel Lake that provides access to Ethel Lake Recreation Area on the northeast shore (FIGURE 2).

The origin of the name "Ethel" is not known, but in the early part of the twentieth century, Ethel Lake was called Bear Lake (Girard 1984). The original inhabitants of the area probably were the nomadic Beaver, Blackfoot and Slavey tribes. Late in the eighteenth century, these tribes were displaced by Cree who came in search of furs to trade with white traders (McMillan 1977). Nearby Cold Lake was part of a fur trade route into Alberta's northern lake region. The first trading post in the area, Cold Lake House, was established by the North West Company in 1781 near the present-day hamlet of Beaver Crossing, about 28 km southeast of Ethel Lake. It was maintained for only a few years, and became a Hudson's Bay post in 1821 when the two companies merged (Alta. Mun. Aff. 1978).

Ethel Lake Recreation Area is operated by Alberta Recreation and Parks. It is open from Victoria Day to Thanksgiving Day and provides 14 campsites, a picnic shelter, a boat launch and pump water. Favoured recreational activities at the lake include fishing, swimming, canoeing, water skiing and power boating. There are no boating restrictions over most of the lake, but in posted areas, power boats are subject to a maximum speed of 12 km/hour (Alta. For. Ld. Wild. 1988).

Ethel Lake's water is quite clear and the concentration of algae is generally low. The shoreline is ringed by dense beds of aquatic vegetation that restrict boat access to some areas, particularly the southeast bay. Species of sport fish in the lake include lake whitefish, northern pike, yellow perch and walleye. The lake's tributaries and outlet stream are closed to sport fishing during a designated period in April and May each year (Alta. For. Ld. Wild. 1989). A small commercial fishery, which operates every other year, mainly harvests lake whitefish from the lake.

Drainage Basin Characteristics

Ethel Lake's gross drainage basin covers an area of 542 km2, which is about 110 times the size of the lake (Tables 1, 2; FIGURE 1). Approximately 11% of this area consists of permanent bodies of water. Three-quarters of the water flowing into Ethel Lake comes from the north: from Burnt Lake, through May and Marie lakes, to Ethel Lake via Marie Creek. A smaller amount of water (20%) flows into Ethel Lake from Moore and Hilda lakes to the west (Alta. Mun. Aff. 1980). The remaining inflows originate from the immediate drainage basin (FIGURE 1), which is quite small (34 km2). These inflows include precipitation, runoff and water from a small stream that flows into the southeast bay.

Ethel Lake and its drainage basin lie on a rolling morainal plain that is characterized by undulating to gently rolling topography (Kocaoglu 1975). Minor ridges and knobs are intermixed with numerous wet depressions and small peat bogs. The main soils throughout the drainage basin are moderately well drained Orthic Gray Luvisols of either a loam or loamy sand type. These soils formed on fine loamy, moderately to strongly calcareous glacial till. Other common soils include Degraded Eutric and Dystric Brunisols, Brunisolic Gray Luvisols and Mesisols.

Ethel Lake's immediate drainage basin is part of the Dry Mixedwood Subregion of the Boreal Mixedwood Ecoregion, whereas the remainder of the drainage basin is part of the Moist Mixedwood Subregion (Strong and Leggat 1981). The difference between the two subregions is the dominance of balsam poplar. In the dry subregion, trembling aspen is the dominant tree on well-drained to moderately well-drained Gray Luvisols, whereas in the moist subregion, trembling aspen and balsam poplar are dominant on moderately well-drained Gray Luvisols. In both subregions, jack pine grows on rapidly to well-drained Eutric Brunisols and white spruce grows on imperfectly drained Gleysols and Gray Luvisols. Poorly drained Organics and Gleysols support a cover of black spruce and willows, and very poorly drained Organic soils support sedges. Wet, low-lying areas are located along the inflow from Hilda Lake, along Marie Creek at the outlet, and southeast and northeast of Ethel Lake.

Most of the land in the drainage basin is classified as marginal for agriculture, and only a few areas have been cleared (FIGURE 1). Agricultural land use includes a few small mixed-farming operations that raise either forage crops and livestock or cash and forage crops. As well, some Crown land is leased for grazing (Alta. Mun. Aff. 1980). Resource extraction is a major industry in the area. Four companies hold leases for oil sands, petroleum and natural gas extraction in the drainage basin, and two Esso Resources Canada heavy oil pilot projects are situated 1.6 km and 6.5 km northwest of the lake. A large gravel deposit is located immediately north of the lake, adjacent to Marie Creek.

About half of the Ethel Lake shoreline is Crown land (FIGURE 2). Long-term recreational leases are held by the Girl Guides, the Boy Scouts and the St. Thomas Aquinas Parents and Teachers Association (Alta. Mun. Aff. 1980). Residential development of the shoreline is limited. A small cottage development and several permanent residences are located on the northeast shore. They are accessible from a gravel road that runs south from the recreation area; one cottage on the northwest shore is located near the inlet from Marie Creek.

Lake Basin Characteristics

Ethel Lake consists of four bays: a deep southwest bay with a maximum depth of 30 m, two northern bays with maximum depths of 8 m and 6 m, and a shallow southeast bay with a maximum depth of 3 m (FIGURE 2). The southeast bay contains dense beds of aquatic macrophytes. The bottom sediments in the lake consist of organic mud and sand overlying clay. Sandy beaches are located at the recreation area in the northeast bay and on private land near the inlet from Hilda Lake in the southwest bay (McGregor 1983).

In the early 1980s, Alberta Environment initiated studies of the Cold Lake-Beaver River basin to ensure wise management of the basin's water resources and to resolve concerns regarding high demand on local water supplies (Alta. Envir. 1983). A long term plan for water resources management in the Cold Lake region was adopted by the government in October 1985. The long term water management plan applies to the surface and groundwater resources in the Cold Lake and lower Beaver River basins. It is based on long term industrial water supply to oil sands plants in the region by a pipeline from the North Saskatchewan River.

Ethel Lake has been used as a source of water by Esso Resources Canada since 1965, when the company was licenced to withdraw 0.802 x 106 m3/year for the Leming oil sands pilot plant. The total allocation was increased to 1.54 x 106 m3/year in 1974, to serve the new May/Ethel plant in addition to the Leming plant (Alta. Envir. n.d.[e]). From 1984 to 1987, Esso withdrew an average of 0.487 x 106 m3/year, or about 1.5% of the lake's total volume. This volume of water is less than 3% of the lake's mean annual outflow of 17.4 x 106 m3. In 1985, as part of the long-term water management plan, Alberta Environment set a minimum elevation of 540.72 m for Ethel Lake (Alta. Envir. 1985). If the lake level fell to this elevation, industrial water withdrawals would be suspended. In addition, it was recommended that over the short term, withdrawals should be limited to 0.700 x 106 m3/year, and the Esso Resources licence was changed accordingly. After the water pipeline to the North Saskatchewan River is completed, Ethel Lake will no longer be used as a major source of water for oil sands plants.

The elevation of Ethel Lake has been monitored since 1973 (FIGURE 3). Water levels declined slightly after August 1978, when a property owner removed a beaver dam from Marie Creek (Alta. Envir. n.d.[e]). In March 1980, Esso constructed a weir in Marie Creek to raise the lake level and ensure a constant supply of water for their two pilot plants (Alta. Mun. Aff. 1980). In 1983, Alberta Environment proposed a higher range of lake levels for Ethel Lake. These levels could not be achieved with Esso's old weir, so a new, steel sheet-piling control structure with a higher sill elevation was planned. In May 1986, the new structure was completed and ownership was transferred from Esso to Alberta Environment. The dam has a main weir, a slightly lower narrow weir to maintain downstream flow, and a Denil II fishway to allow fish passage upstream into the lake (TABLE 2). Water levels reached an historic high in September 1986 (FIGURE 3) after the control structure was completed. These levels were due to beaver dams downstream of the lake, not the control structure. The range in lake levels over the period of record is 0.81 m. Changes in the lake's area and capacity with fluctuations in water level are illustrated in Figure 4.

Water Quality

The water quality of Ethel Lake has been studied intensively by Alberta Environment since 1978 (Alta. Envir. n.d.[b]; Prepas and Trew 1983; Trew et al. 1983) and was studied by the University of Alberta in 1981 (Prepas 1983). Ethel Lake is one of six lakes in Alberta that have an extensive long-term data base for water quality.

The water in Ethel Lake is fresh and well-buffered (TABLE 3). Bicarbonate and calcium are the dominant ions. The ionic composition of the water reflects the inflow from other lakes in the Marie Creek drainage basin. The concentration of total dissolved solids in Ethel Lake is lower than that in Moore and Hilda lakes, to the west, and higher than that in Marie and May lakes, to the north (Alta. Envir. n.d.[b]).

Ethel Lake is sheltered by trees and has a short fetch. Consequently, winds over the deep basin often are not strong enough to mix the water column in spring. Data for mid- to late May are available for 8 of the 11 years from 1978 to 1988. In five of the eight years, the lake did not mix to the bottom and the deepest water was anoxic. In the other three years, the amount of mixing was variable. In mid-May of 1982, the temperature of the water column was uniform (FIGURE 5), but an oxygen gradient was recorded: dissolved oxygen concentrations ranged from 10.6 mg/L at the surface to 8.6 mg/L at the bottom (FIGURE 6). The deeper water becomes anoxic every year during summer, when the lake is thermally stratified. The water column usually mixes to the bottom, however, by late October. Exceptions occurred in October of 1979 and 1982, when dissolved oxygen concentrations in the deep basin were less than 1 mg/L at the bottom. Under ice, the deep water in the southwest bay of Ethel Lake frequently becomes anoxic by February or March, as in 1980, 1981, 1982, 1984 and 1989, or severely depleted in dissolved oxygen, as in 1983, 1986, 1987 and 1988. Surface concentrations, however, have always exceeded 8 mg/L in late winter. The thermal and dissolved oxygen patterns in the deep basin of Ethel Lake are similar to those in many deep lakes in eastern Alberta.

Ethel Lake is mesotrophic. The water is generally clear and attractive for most of the summer because concentrations of algae are low. In 1982, the Secchi depth averaged 3.1 m (TABLE 4). From 1980 to 1987, year-to-year variations in the average total phosphorus concentration from mid-June to mid-September were less than the variations in chlorophyll a concentrations (TABLE 5). In summer each year, the surface waters are phosphorus-limited (Prepas 1983), and the highest annual phosphorus and chlorophyll concentrations in the euphotic zone (FIGURE 7) usually occur after the spring and fall overturn, when phosphorus-rich water from near the sediments is mixed into the surface water.

Phosphorus is released from the bottom sediments of the lake during anoxic periods. In the summer of 1982, the phosphorus concentration at a depth of 30 m increased from about 80 µg/L in mid-June to 220 µg/L in mid-September. Phosphorus levels in the surface water, on the other hand, remained relatively stable during this period. Loading of total phosphorus to Ethel Lake from internal and external sources was calculated for the period from 15 May to 30 October in 1982 (TABLE 6). The greatest portion of the total phosphorus load (69%) originated from internal sources. Precipitation and dustfall provided 15% of the load, sewage and runoff from residential areas contributed 12% and inflow from other lakes accounted for 5%. In a separate study, the internal loading of total phosphorus from sediments in the euphotic zone (to a depth of 8 m) to the overlying water was calculated to be an average of 4.35 kg/day for the period from 23 May to 26 August 1980 to 1984, and 1986 and 1987 (Shaw and Prepas 1989).

Biological Characteristics


The phytoplankton in Ethel Lake was studied briefly by Esso Resources Canada in 1978 (Cross 1979). As well, phytoplankton was studied by Alberta Environment bimonthly during the open-water period from 1980 to 1982, monthly under ice in 1980 and monthly during the open-water period from 1983 to 1986 (Alta. Envir. n.d.[b]).

The biomass of algae in Ethel Lake is low. From 1980 to 1986, the mean annual biomass ranged from a low of 1.44 mg/L in 1986 to a high of 3.40 mg/L in 1980 (TABLE 7). The maximum biomass each year was observed either in spring (May or June) or fall (September or October). These peaks were usually dominated by either blue-green algae (Cyanophyta) or diatoms (Bacillariophyta), except in 1982, when Pyrrhophyta was dominant (TABLE 7). Low dissolved oxygen conditions over the bottom sediments and moderately high total phosphorus levels enhance the development of blue-green algae in Ethel Lake (Trimbee and Prepas 1987; 1988).

In 1982 (TABLE 8), diatoms (mostly Cyclotella compta, C. meneghiniana, Asterionella formosa and Fragilaria crotonensis) and cryptophytes (mostly Katablepharis ovalis, Cryptomonas erosa, C. Marsonii and C. rostratiformis) formed a large part of the biomass from mid-May to early July and from late September to late October. Pyrrhophyta were the dominant or codominant group in May (mainly Peridinium africanum and P. palatinum) and from late July to early September (mainly Ceratium hirundinella). Blue-greens (mainly Lyngbya birgei, Anabaena flos-aquae, Aphanothece sp. and Aphanizomenon flos-aquae) formed more than 20% of the biomass from late July to late September, and golden-brown species (Chrysophyta: mainly Chrysochromulina parva) were important in late May and early June.

The aquatic macrophytes of Ethel Lake were surveyed in 1978 by Alberta Environment (FIGURE 8). The lake supports dense growths of aquatic macrophytes, particularly in the shallow southeast bay, which is filled with submergent species. The main submergent species are large-sheath pondweed (Potamogeton vaginatus), Richardson pondweed (P. richardsonii) and northern watermilfoil (Myriophyllum exalbescens). Submergent plants grow to a depth of 4.8 m (Chambers and Prepas 1988). Much of the lake is ringed with emergent species, which often block access to the southeast bay. The dominant emergent species are reed grass (Phragmites communis), common cattail (Typha latifolia) and common great bulrush (Scirpus validus).


A brief survey of the zooplankton and benthic invertebrate communities in Ethel Lake was conducted for Esso Resources Canada during 1978 (Cross 1979). Based on five samples collected from 2 March to 10 December, the dominant copepod was Diacyclops bicuspidatus thornasi (range 12.2 to 291.6/L) throughout most of the year, except in October, when the rotifer Keratella cochlearis was extremely abundant (1,363.7/L). The most abundant cladoceran was Chydorus sphaericus (range 14.7 to 230.6/L), particularly in October.

A total of six dredge samples were taken in the littoral zone (2.5-m to 4.8-m deep) on 19 July and 26 October in 1978. The dominant taxonomic group by number on both dates was midge larvae (Chironomidae), with a large number of scuds (Amphipoda: Hyalella azteca) recorded in October. A small number of roundworms (Nematoda), mayfly nymphs (Ephemeroptera), caddis fly larvae (Trichoptera), aquatic earthworms (Oligochaeta), snails (Gastropoda: mostly Physa) and fingernail clams (Pelecypoda: Sphaeriurn) were also recorded. As well, a total of 18 dredge samples were collected in the profundal zone (7-m to 24-m deep) on five sampling dates from 2 March to 10 December. Snails, which were found in May and October, included round-mouthed snails (Valvatidae) and pouch snails (Physidae). Small numbers of clams (mostly Pisidium and Sphaerium) were found on all but one sampling date, and aquatic earthworms, leeches (Hirudinea) and mayfly nymphs were found less frequently. The data for both littoral and profundal zones are too few to allow estimation of the total abundance, total biomass or relative abundance of benthic invertebrates.


Eleven species of fish have been reported in Ethel Lake: northern pike, yellow perch, walleye, lake whitefish, cisco, burbot, longnose sucker, white sucker, spottail shiner, ninespine stickleback and Iowa darter (Aquat. Envir. Ltd. 1983; Longmore and Stenton 1983). The lake whitefish and cisco are infested with cysts of the tapeworm Triaenophorus crassus (Alta. Rec. Parks Wild. 1976).

Detailed information on fish spawning habitats is not available, but important areas are probably located at the mouths of inlets. Potentially important areas for pike and perch are the shallow vegetated sections of the southeast bay, the shoreline running south from this bay, and the area near the point of land on the west shore. Spawning areas for walleye and whitefish are probably located in sandy areas off the northwest and northeast shores (Alta. Mun. Aff. 1980).

Ethel Lake's commercial fishery first opened during the 1944/45 season (Alta. For Ld. Wild. n.d.; Alta. Rec. Parks Wild. 1976). The largest total catch (10,945 kg) ever taken in the lake was recorded that year; it was mainly composed of cisco (73%) and lake whitefish (22%). The fishery was closed from 1945/46 to 1951/52. Since 1952/53, the size of the total catch and the proportions of cisco and lake whitefish have fluctuated considerably. Since 1972/73, whitefish have formed the major portion of the catch. During the 1980s, the fishery opened only in alternate years. In 1987/88, the total catch of lake whitefish, walleye, northern pike and cisco was 4,343 kg; 92% of this catch was lake whitefish.

A creel survey was conducted at Ethel Lake from 17 May to 14 August in 1986 (TABLE 9). Northern pike was the main species caught, with smaller amounts of yellow perch and walleye also taken. Of the total number of each species caught, none of the walleye, 13% of the yellow perch and 55% of the northern pike were released. The harvest rates for walleye (0.02/angler-hour) and yellow perch (0.04/angler-hour) are well below the average rates for 22 lakes in the region (0.10 walleye/angler-hour and 0.32 perch/angler-hour), but the harvest rate for northern pike (0.37/angler-hour) is well above the regional average (0.22 pike/angler-hour).


With the exception of the southeast bay, most of the Ethel Lake shoreline is only moderately productive for waterfowl. Habitat is limited by reduced marsh edge and deep water. The species of birds sighted at the lake include Mallard, American Widgeon, Lesser Scaup, Red-necked Grebe, Western Grebe, American Coot, Common Loon, Common Tern and American Bittern. A colony of Western Grebes is located on the south shore where the southeast bay joins the main part of the lake (Alta. Mun. Aff. 1980; Rippon 1983).

M.E. Bradford


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