|Lat / Long||53.6333333, -114.7333333|
|Max depth||7.5 m|
|Mean depth||4.1 m|
|Dr. Basin Area||246 km2|
|Drainage Basin||North Saskatchewan River Basin|
|Sport Fish||Northern Pike, Walleye, Yellow Perch|
|TP x||101 µg/L|
|CHLORO x||39.2 µg/L|
|TDS x||164 mg/L|
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.
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
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).
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.
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 eg
Alberta Environment. n.d.[a]. Envir. Assess. Div., Envir. Qlty. Monit. Br. Unpubl. data, Edmonton.
-----. n.d.[b]. Tech. Serv. Div., Hydrol. Br. Unpubl. data, Edmonton.
-----. n.d.[c]. Tech. Serv. Div., Surv. Br. Unpubl. data, Edmonton.
-----. 1977. Interim report-Sturgeon River basin study. Plan. Div., Edmonton.
-----. 1980. Isle Lake/Lac Ste. Anne regulation feasibility study-summary report. Plan. Div., Edmonton.
-----. 1989. Lake Isle. Envir. Assess. Div., Envir. Qlty. Monit. Br., Edmonton.
Alberta Forestry, Lands and Wildlife. 1987. A summary of Alberta's natural areas reserved and established. Pub. Ld. Div., Ld. Mgt. Devel. Br. Unpubl. rep., Edmonton.
-----. 1988. Boating in Alberta. Fish Wild. Div., Edmonton.
-----. 1989. Guide to sportfishing. Fish Wild. Div., Edmonton.
Alberta Recreation, Parks and Wildlife. 1976. Commercial fisheries catch statistics for Alberta, 1942-1975. Fish Wild. Div., Fish. Mgt. Rep. No. 22, Edmonton.
Alberta Research Council. 1972. Geological map of Alberta. Nat. Resour. Div., Alta. Geol. Surv., Edmonton.
Chambers, P.A. and E.E. Prepas. 1988. Underwater spectral attenuation and its effect on the maximum depth of angiosperm colonization. Can. J. Fish. Aquat. Sci. 45:1010-1017.
Dempsey, H.V. 1945. A biological examination of Isle Lake. Alta. Ld. Mines, Fish Game Admin. Unpubl. rep., Edmonton.
Edmonton Regional Planning Commission. 1983. Lake Isle management study. Edm. Reg. Plan. Commis., Edmonton.
Energy, Mines and Resources Canada. 1974. National topographic series 1:50 000 83G/7 (1974), 83G/10 (1974). Surv. Map. Br., Ottawa.
Environment Canada. 1972-1987. Surface water data. Prep. by Inland Waters Directorate. Water Surv. Can., Water Resour. Br., Ottawa.
-----. 1982. Canadian climate normals, Vol. 7: Bright sunshine (1951-1980). Prep. by Atm. Envir. Serv. Supply Serv. Can., Ottawa.
Hawryluk, R.W. 1980. An overview of fisheries data for Lake Isle. Alta. En. Nat. Resour., Fish Wild. Div. Unpubl. rep., Edmonton.
Holmgren, E.J. and P.M. Holmgren. 1976. Over 2000 place names of Alberta. 3rd ed. West. Producer Prairie Books, Saskatoon.
Klarer, D.M. and M. Hickman. ca 1977. A paleolimnological study of Lake Isle, Alberta. Prep. for Alta. Envir., Water Qlty. Cont. Br., Edmonton.
Lane, C.B. 1971. A survey of the fishery resources of Isle, Lac Ste. Anne and Matchayaw or Devils Lake, 1969. Alta. Ld. For., Fish Wild. Div. Unpubl. rep., Edmonton.
Lindsay, J.D., W. Odynsky, J.W. Peters and W.E. Bowser. 1968. Soil survey of the Buck Lake (NE 83B) and Wabamun Lake (E1/2 83G) areas. Alta. Soil Surv. Rep. No. 24, Univ. Alta. Bull. No. SS-7, Alta. Res. Counc. Rep. No. 87. Univ. Alta., Edmonton.
Miller, R.B. and M. Paetz. 1953. Preliminary biological surveys of Alberta watersheds 1950-1952. Alta. Ld. For., Fish Wild. Div., Edmonton.
Mitchell, P.A. 1982. Evaluation of the "septic snooper" on Wabamun and Pigeon lakes. Alta. Envir., Poll. Contr. Div., Water Qlty. Contr. Br., Edmonton.
-----. 1984. Water quality in Lake Isle-1983. Alta. Envir., Poll. Contr. Div., Water QIty. Contr. Br., Edmonton.