Isle 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 is out of date.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 Sheets83G/10
Lat / Long53.6333333, -114.7333333
53°37'N, 114°43'W
Area23.0 km2
Max depth7.5 m
Mean depth4.1 m
Dr. Basin Area246 km2
Dam, WeirNone
Drainage BasinNorth Saskatchewan River Basin
Camp GroundPresent
Boat LaunchPresent
Sport FishNorthern Pike, Walleye, Yellow Perch
Trophic StatusHyper-Eutrophic
TP x101 µg/L
CHLORO x39.2 µg/L
TDS x164 mg/L
Photo credit: unknown


Scenic Isle Lake is located in the counties of Parkland and Lac Ste. Anne. It is situated about 80 km west of the city of Edmonton, immediately north of Highway 16. The hamlet of Gainford is located on the southwestern shore (FIGURE 1). Unpaved Secondary Road 633 follows the northern shore of the lake and joins Highway 33 just southeast of Lac Ste. Anne.

The lake's name refers to the presence of several islands. In the past Isle Lake was called Lac des Isles and Lac des Islets (Holmgren and Holmgren 1976); now it is known locally as Lake Isle.

In 1870, the Hudson's Bay Company built a trading post beside Lac Ste. Anne, about 14 km northeast of Isle Lake (Lindsay et al. 1968). The wooded region around Isle Lake was settled after 1905 when lands became available for agriculture. The first subdivision was registered at Gainford in 1942 and the most rapid development of land around the lake occurred between 1955 and 1964. In 1980, there were 18 registered subdivisions with a total of 1 038 lots; 736 lots were developed (Edm. Reg. Plan. Commis. 1983). Several of these subdivisions are incorporated into two summer villages, Silver Sands and South View, on the eastern end of the lake (FIGURE 2).

Access to the lake is available at numerous municipal reserves that provide boat launches, parks, access points or walkways (Edm. Reg. Plan. Commis. 1983). Gainford Park day-use area, operated by the County of Parkland, provides picnic tables and a gravel boat launch. As well, there are two public campgrounds (FIGURE 2). Gainford Campground, operated by Alberta Transportation and Utilities, is located on Highway 16, about 1 km west of Gainford; it has eight campsites, a picnic shelter, picnic tables and a water pump. The Kokomoko Recreation Area, which is owned by the County of Parkland, is located on the southern shore. Its facilities include 10 campsites, picnic tables and a gravel boat launch. There are also a number of church operated and commercially operated recreational facilities that have campgrounds and trailer parks with boat launching, swimming and picnicking facilities. Camp He-Ho-Ha on the southern shore is operated by the Alberta Rehabilitation Council for the Disabled; it provides outdoor recreation facilities for handicapped children. Swimming, boating and fishing are favoured recreational activities at Isle Lake. In posted areas of the lake boats may be prohibited or subject to a maximum speed of 12 km/hour (Alta. For. Ld. Wild. 1988).

A small proportion of the land adjacent to Isle Lake, and all of the islands in the lake, are Crown land (FIGURE 2). Most of it is maintained in its natural state except for the portion containing Camp He-Ho-Ha (Edm. Reg. Plan. Commis. 1983). Two quarter sections south of Camp He-Ho-Ha were established as a Natural Area for recreation in 1971 and some trails have been developed there (Alta. For. Ld. Wild. 1987).

Isle Lake commonly has blooms of blue-green algae during summer, and aquatic vegetation grows extensively throughout much of the lake. Although low levels of dissolved oxygen sometimes cause summer and winter fish kills, northern pike and walleye support a popular sport fishery. All tributary streams to, and the outlet from, the lake are closed to fishing for a period in spring (Alta. For. Ld. Wild. 1989). The actual closing and opening dates may vary from year to year.

Drainage Basin Characteristics

The drainage basin of Isle Lake is about 11 times the size of the lake (Tables 1, 2). Most surface water flows into the lake from the southwest through the Sturgeon River (FIGURE 1). The outflow from Dussault and Round lakes, situated northwest of Isle Lake, drains into the Sturgeon River shortly before the river enters Isle Lake. Several intermittent streams drain the remainder of the drainage basin. The lake's outlet, the Sturgeon River, is located at the eastern end; it flows eastward to the North Saskatchewan River via Lac Ste. Anne, Matchayaw Lake and Big Lake.

A detailed study of the water resources of the Sturgeon River basin was completed in 1977 (Alta. Envir. 1977). The report examined flooding problems, water-based recreation, fish and wildlife resources and water supply concerns.

Four bedrock formations underlie Isle Lake. The lowermost, Horseshoe Canyon Formation, is lithologically complex, which results in groundwater conditions that differ markedly from area to area. Overlying the Horseshoe Canyon Formation are the relatively impermeable Whitemud and Battle formations. The Paskapoo Formation lies nearest the surface and offers the most reliable source of groundwater; this formation contains the Ardley coal zone, which is mined at nearby Wabamun Lake. Saskatchewan sands and gravels overlie the bedrock and are characterized by extremely good water availability (Edm. Reg. Plan. Commis. 1983).

Most of the drainage basin is characterized by gently rolling (5 to 9% slope) to moderately rolling (9 to 15% slope) terrain. There is a strongly rolling region (greater than 15% slope) just southwest of the lake (Lindsay et al. 1968). Surficial deposits appear closely related to the underlying bedrock. The undulating ground moraine that covers most of the drainage basin is composed of glacial till, and lesser amounts of glaciolacustrine deposits are present. Organic deposits occur in depressions throughout the basin, and beach sands occur around the shoreline (Twardy and Brocke 1978).

The dominant soils in the watershed are moderately well-drained Orthic Gray Luvisols, which are developed on a variety of glacial materials, but mainly till. Moderately well-drained Dark Gray Luvisols developed on glaciolacustrine or glaciofluvial materials are also present in the western portion of the area; these are some of the better agricultural soils near Isle Lake. Eluviated Eutric Brunisols developed on very coarse materials are present south and northeast of the lake. Small areas of Organic soils, characterized by more than 50 cm of compacted sedge or moss peat, occur throughout the drainage basin (Twardy and Brocke 1978).

Sand and gravel are the most important nonrenewable resources presently extracted in the watershed. Coal, oil and natural gas deposits are not yet being exploited to any great extent (Edm. Reg. Plan. Commis. 1983).

About 54% of the drainage basin is forested and 45% is open or has been cleared for agriculture (FIGURE 1). The remaining 1% has been developed for cottages and permanent residences. Trembling aspen is the dominant tree on well-drained sites, and balsam poplar, white spruce and willow grow in more poorly drained areas (Edm. Reg. Plan. Commis. 1983). A sedge fen is located around the inlet of the Sturgeon River. Most of the natural vegetation immediately surrounding the lake is relatively undisturbed (R. L. & L. Envir. Serv. Ltd. 1987). Beef cattle production is a prominent agricultural activity in the region (Olson 1988), and part of the Jackpine Grazing Reserve is located in the southern portion of the drainage basin.

Most of the lakeshore is privately owned. In 1977, Isle Lake became subject to the Regulated Lake Shoreland Development Operations Regulations, which were administered by Alberta Environment. The regulations prohibited most developments at the lake until an area redevelopment plan and area structure plan were prepared at the direction of the councils of the counties of Lac Ste. Anne and Parkland and the summer villages of Southview and Silver Sands (Yell. Reg. Plan. Commis. 1984). Such plans determine the extent of future land developments, allocate land use and determine ways to minimize environmental impacts and conflicts in uses of the lakeshore. They recommend preferred lake uses and ways to minimize lake-user conflicts.

Lake Basin Characteristics

Isle Lake is long, narrow and fairly shallow (FIGURE 2). It is a medium-sized lake, with a surface area of 23 km2. The maximum depth, near the middle of the lake, is only about 7.5 m. The lake is divided into a small, shallow western basin and a slightly larger and deeper eastern basin. There are about eight islands in the eastern basin. The littoral zone extends to 3.8 m (as calculated from Chambers and Prepas 1988) and occupies 40% of the surface area of the lake (FIGURE 3).

The lake bottom is quite irregular. Slopes are steep near shore but the bottom is fairly flat in deeper water, except for scattered knobs and islands. Sand is located around much of the perimeter of the lake and around several of the islands. There are also small localized regions of gravel, rubble and boulders, and clay and fibrous organic substrates in small patches along the shore (R.L. & L. Envir. Serv. Ltd. 1987). Sediment cores were examined in 1977 to determine the environmental history of the lake and its drainage basin; erosion rates have remained fairly constant, and the lake has probably been eutrophic for the last 4,000 years (Klarer and Hickman 1977).

As with other lakes in the area, the water level fluctuation in Isle Lake has elicited complaints from property owners. Between 1960 and 1987 the water level varied over a range of 1.5 m, from a recorded high of 730.72 m in 1965 to a recorded low of 729.22 m in 1968 (FIGURE 4). A few complaints about the low water level in 1968 were registered, but high water levels have generated more concern. Alberta Environment studied the feasibility of regulating the water levels of Isle Lake and Lac Ste. Anne in 1979 and 1980. Regulation of water levels in Isle Lake was not considered feasible (Alta. Envir. 1980).

Water Quality

Alberta Environment studied the water quality of Isle Lake between 1983 and 1985 (Alta. Envir. n.d.[a]; 1989; Mitchell 1984). Data were also collected on 20 August 1986 (R.L. & L. Envir. Serv. Ltd. 1987).

Isle Lake is a freshwater lake; the dominant ions are calcium and bicarbonate (TABLE 3). The clarity of the water is fairly poor because algal growth is heavy during the open-water period.

Because the lake is shallow, large and exposed to the prevailing westerly winds, its waters mix from the surface to the bottom on most days during the open-water season. The water column is weakly thermally stratified on hot, calm days (FIGURE 5). During the period between June and August in 1984 (FIGURE 6), dissolved oxygen levels were lower over the bottom sediments than in water at the surface; in late summer, concentrations dropped to 1 mg/L near the bottom. Summerkills of fish have been reported in Isle Lake. In January 1984, dissolved oxygen ranged from 10.9 mg/L at 1 m to 3.5 mg/L at the bottom (FIGURE 6). Winter dissolved oxygen data compiled for seven occasions from 1971 to 1985 indicated that dissolved oxygen concentrations in the lake are frequently very low during winter (R.L. & L. Envir. Serv. Ltd. 1987). Partial winterkills of fish sometimes occur.

Isle Lake is classified as hyper-eutrophic. Phosphorus concentrations are very high: in 1984, the peak concentration of total phosphorus exceeded 270 µg/L (FIGURE 7). These high phosphorus concentrations may result from external sources such as runoff from the relatively large watershed of the lake and extensive areas of cleared and agricultural land, and the large number of cattle in the drainage basin (TABLE 5). A 1981 estimate of phosphorus loading to Isle Lake reached similar conclusions (Reynoldson 1981). The release of phosphorus from the sediments is also an important source. For example, in 1984, the quantity of total phosphorus estimated to result from internal loading is about twice the annual external load reported in TABLE 5.

The high nutrient levels in Isle Lake are reflected in its high algal productivity, as indicated by chlorophyll a (TABLE 4). In 1984, phosphorus concentrations rose sharply in late August (FIGURE 7). The most likely source of this phosphorus was the lake bottom sediments. The level of chlorophyll a increased gradually over the summer and transparency declined. These patterns appear to be quite typical for this lake.

Biological Characteristics


Heavy blooms of blue-green algae (Cyanophyta) develop in Isle Lake during July and August. These blooms were noted as long ago as 1952 (Miller and Paetz 1953). Die-offs of the blooms often produce unpleasant odours in late summer and may reduce oxygen levels, which contribute to summerkills of fish.

The composition and biomass of the phytoplankton community was studied by Alberta Environment in 1983 (TABLE 6). In May, the dominant groups were Pyrrhophyta (Peridinium cinctum) and the diatoms Stephanodiscus hantzschia and Asterionella formosa. Blue-green algae were dominant from June to August, likely due to the high phosphorus concentrations (Trimbee and Prepas 1987). In June, Gloeotrichia echinulata and Aphanizomenon flos-aquae were the dominant species. A. flos-aquae was most abundant in July and developed into an intense bloom during August. In the fall, diatoms, particularly Stephanodiscus niagarae, accounted for most of the algal biomass.

Aquatic macrophytes grow extensively in Isle Lake because it is shallow and nutrient-rich. These plants are important as cover, spawning habitat and food sources for fish, but they interfere with swimming, boating and angling. In 1973, the vegetation offshore of Kokomoko Recreation Area was removed by various chemical treatments, with variable success (Worthington 1973). During a survey in September 1986 (R.L. & L. Envir. Serv. Ltd. 1987), narrow bands of emergent species dominated by common great bulrush (Scirpus validus) were found along shallow areas of the shore and around islands (FIGURE 8). Common cattail (Typha latifolia) and sedge (Carex sp.) also were common. Submergent species were abundant between depths of 1 m and 5 m, particularly in the western basin, where they extended 200 m to 300 m from shore.The most abundant submergent species were northern watermilfoil (Myriophyllum exalbescens), which grew along most of the shoreline, and Richardson pondweed (Potamogeton richardsonii).


During a study conducted by Fish and Wildlife Division from June to August 1969, zooplankton was found to be most abundant in early June. The cladoceran Daphnia sp. was present from June to August; the most numerous copepod was Cyclops sp. and the most abundant rotifer was Keratella sp. (Lane 1971).

Benthic invertebrates were sampled during a fisheries study in 1969 (Lane 1971). From an analysis of 47 dredge samples from various depths and bottom types, the average dry weight of bottom fauna was determined to be 5.6 g/m2 (TABLE 7). This was considered to be very high and indicative of the eutrophic condition of Isle Lake. The most numerically abundant invertebrates were midge larvae (Chironomidae) which made up about 55% of the total number in samples; scuds (Amphipoda) accounted for about 26%, and phantom midge larvae (Chaoborus sp.) for 10%. Chironomidae were most numerous on fine-grained substrates in deep water, whereas amphipods were most abundant in shallow water (less than 4 m deep).


Isle Lake is productive for fish. Species that have been reported in the lake are northern pike, yellow perch, walleye, burbot, white suckers, brook stickleback, spottail shiners and fathead minnows (Lane 1971; R.L. & L. Envir. Serv. Ltd. 1987). In 1986 the most numerous species were brook stickleback, northern pike and white suckers (R.L. & L. Envir. Serv. Ltd. 1987). Walleye were very abundant in commercial catches during the 1920s but declined by 1945 (Dempsey 1945). Walleye eggs were planted in the lake in 1953 to supplement the indigenous population but the success of the project was not determined (R.L. & L. Envir. Serv. Ltd. 1987). Partial summerkills of fish were reported in Isle Lake in May 1957, August 1968, July 1970, August 1974 and July 1978 (Hawryluk 1980). Partial winterkills occurred in 1957/58 and 1971/72 (R.L. & L. Envir. Serv. Ltd. 1987).

Northern pike spawn in weedy areas in the western basin of Isle Lake and in the Sturgeon River. Walleye spawn in gravel/cobble areas near the three largest islands in the eastern basin, just west of the "narrows" between the basins, and along the southern shore next to Sunset Beach. Known spawning areas for yellow perch include the inlet and outlet of the Sturgeon River, and the bay at Isle Cove on the southern shore (R.L. & L. Envir. Serv. Ltd. 1987).

Commercial fishing took place on Isle Lake before 1938 and in 1947/48 (Hawryluk 1980). In 1971/72 the lake was fished commercially to salvage fish before a predicted winterkill (R.L. & L. Envir. Serv. Ltd. 1987). That season's total harvest of 8,193 kg consisted of 4,153 kg of white suckers, 3,504 kg of northern pike, 291 kg of walleye, 235 kg of burbot, and 10 kg of yellow perch (Alta. Rec. Parks Wild. 1976). Commercial fishing has not taken place since 1972.

Isle Lake is managed for domestic and recreational fisheries, but there have been no domestic permits issued since 1984 (Watson 1989). Sport fishing is an important activity, both in summer and winter. A 1969 creel survey estimated that, between May and October, 6,851 anglers fished the lake for 21,237 hours. The catch was dominated by northern pike (92%). Walleye accounted for only 7% of the harvest and the catch of yellow perch was negligible. The catch per unit effort was 0.82 fish/angler-hour, which was considered to be a high success rate. Successful walleye fishing occurred primarily during spring and fall. Most anglers use boats because dense macrophyte beds interfere with fishing from the shore (Lane 1971).


Isle Lake and its shore region provide very important wildlife habitat. Part of the southern shore is excellent raptor nesting and breeding territory; Ospreys nest by the lake. Important areas for waterfowl are located at the outlet and at the western end of the lake, including the marsh by the Sturgeon River inlet. The islands and shallow, weedy areas in the lake and along its shore also provide good breeding, nesting and brood-rearing habitat. In addition, Isle Lake is an important waterfowl staging area for fall migration. Common ducks include Bufflehead, Common Goldeneye, Lesser Scaup and Mallards. A nesting colony of Great Blue Herons was noted in 1981. Beaver habitat is located on the western and northern shores of the lake (Edm. Reg. Plan. Commis. 1983).

L. Hart Buckland-Nicks and P.A. Mitchell


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