Iosegun 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 is out of date.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 Sheets83K/7, 10
Lat / Long54.4666667, -116.8333333
54°28'N, 116°49'W
Area13.4 km2
Max depth11.2 m
Mean depth4.1 m
Dr. Basin Area248 km2
Dam, WeirWeir
Drainage BasinSmoky River Basin
Camp GroundPresent
Boat LaunchPresent
Sport FishNorthern Pike, Lake Whitefish, Walleye, Yellow Perch
Trophic StatusEutrophic
TP x61 µg/L
CHLORO x26.6 µg/L
TDS x83 mg/L
Photo credit: D. Huet


Iosegun Lake is a popular sport fishing lake set in heavily forested, gently rolling land. It is situated in Improvement District No. 16, 260 km northwest of the city of Edmonton, 82 km northwest of the town of Whitecourt and 8 km north of the town of Fox Creek. An industrial road from Fox Creek serves the east side of the lake (FIGURE 1) and provides access to Iosegun Lake Forest Recreation Area.

The lake's name originates from a Cree or Stoney word for the Iosegun River that means either "tail" or "hash" (Alta. Cult. Multicult. n.d.). The lake was called Hash Lake by fur traders and natives in the early 1900s.

The native inhabitants in the area northwest of Whitecourt were Woodland Cree, but the Beaver tribe may have lived there at an earlier time (Olecko 1974). The region was close to an aboriginal migration route from Lac Ste. Anne to the Sturgeon Lake area, and sites on Iosegun Lake have traditionally been used as hunting and fishing bases. As well, four sites near the lake have been identified as burial grounds (Alta. For. Ld. Wild. 1988[b]).The first European to arrive in the area was probably David Thompson in 1799; he camped at a site that is now the Whitecourt townsite (Knapik and Lindsay 1983). Missionaries arrived in the region about 40 years later. Industrial development began in 1909 when logging and milling operations were initiated 10 km west of Whitecourt near the Athabasca River. The railroad arrived in Whitecourt in 1921, but was never completed to the Peace River Country, as originally proposed. The area near Iosegun Lake was not developed until oil and gas exploration in the 1950s brought the railroad as far as the Kaybob station, about 15 km south of the lake. Highway 43 opened in 1955, and was paved and completed in 1962 as far as the town of Valleyview, 70 km north of the lake. There have been no residential developments at the lake.

In 1988, a lake management plan for Iosegun Lake was completed by Alberta Forestry, Lands and Wildlife (Alta. For. Ld. Wild. 1988[b]). The plan assesses potential commercial and public recreational development of Iosegun Lake, based on environmental, social and economic constraints. It will be used as the basis for an area structure plan to guide development around the lake, which will be prepared by improvement District No. 16.

Iosegun Lake Forest Recreation Area was built in 1970 by the Alberta Forest Service and upgraded in 1986. It is located at the southeast end of the lake (FIGURE 2), and serves as a staging area for the Alberta Forest Service's Iosegun Lake Snowmobile Trails. Facilities at the recreation area include 50 campsites, a day-use area with 10 picnic tables, a picnic shelter, pump water, a beach and a boat launch. Popular activities on and around the lake are power boating, wind surfing, fishing, picnicking, swimming, cross-country skiing and snowmobiling. There are no boating restrictions specific to Iosegun Lake, but general federal regulations apply (Alta. For. Ld. Wild 1988[a]).

Algal blooms turn the lake water green in late summer, and aquatic vegetation grows in shallow areas at the north end. High concentrations of organic matter reduce water clarity. The main catches of the sport fishery are walleye and northern pike. Iosegun Lake is closed to sport fishing during a designated period in April and May each year. As well, the lake's inlet and outlet streams are closed to fishing from September to mid-June each year (Alta. For. Ld. Wild. 1989). A commercial fishery operates in alternate years.

Drainage Basin Characteristics

Iosegun Lake has a large, extensively forested drainage basin that is about 19 times the size of the lake (Tables 1, 2). Raspberry Lake and several intermittent and permanent streams flow into Iosegun Lake (FIGURE 1). Water leaves the lake at the north end via Outlet Creek, which flows into the Iosegun River, a major tributary of the Little Smoky River.

The drainage basin is part of the Iosegun Plain physiographic division and is underlain by nonmarine sandstones, silty mudstones and coal beds covered by glacial drift (Knapik and Lindsay 1983). The land is undulating to gently rolling and the soils are mainly Orthic Gray Luvisols that developed on clay-loam textured glacial till, and Gleyed Solonetzic Gray Luvisols that developed on glaciolacustrine clays. Extensive areas of very poorly drained Mesisols are located throughout the drainage basin, mainly along inflowing streams.

The watershed is part of the Moist Mixedwood Subregion of the Boreal Mixedwood Ecoregion. Trembling aspen, which is the dominant vegetation, is replaced by balsam poplar in depressions. White spruce and balsam fir stands grow in scattered locations that have escaped recent fires, and willows, sedges and black spruce grow on poorly drained soils (Strong and Leggat 1981; Knapik and Lindsay 1983).

Only about 1% of the land has been cleared for agricultural use. Soil limitations for agriculture are severe - soils are imperfectly drained and dry slowly after becoming wet. There is, however, forestry and natural gas activity in the area. Iosegun Lake is located on the Kaybob Oil and Gas Field; many wells are located east of the lake and the area is criss-crossed by pipelines that carry oil and gas to processing plants.

Lake Basin Characteristics

Iosegun Lake is a medium-sized lake that is 8-km long and 2-km wide (TABLE 2). The slope of the lake basin is relatively gentle at the north and south ends and steep on the east and west sides. The deepest spot (11.2 m) is located near the centre of the lake (FIGURE 2). The large bay at the north end is very shallow and supports dense beds of aquatic plants. A sand and mud beach is located at the recreation area on the southeast shore. Sections of the east shore are rocky, and most of the west and north shores are swampy (Hartman 1957).

A water-pumping station owned by Chevron Canada Resources Limited is located on the eastern shore. Between 1981 and 1988, Chevron's annual water allocation was 1.480 x 106 m3. Actual withdrawals, however, were much less: they ranged from a high of 1.056 x 106 m3 in 1982 to a low of 0.5884 x 106 m3 in 1987 (Alta. Envir. n.d.[e]).

The elevation of Iosegun Lake has been monitored since 1975 (FIGURE 3). Over the period of record, the minimum elevation was 773.17 m, recorded in October 1981, and the maximum elevation was 774.41 m, recorded in June 1985. A fluctuation of this magnitude (1.24 m) would change the surface area of the lake by about 18% (FIGURE 4). The maximum lake level occurred the year after Alberta Environment built a sheet-pile weir across Outlet Creek to stabilize water levels. The minimum crest elevation of the weir is 773.70 m (TABLE 2), so water will flow out of the lake when the lake level is above this elevation. Since the weir was installed in 1984, the water level has stabilized. The amplitudes of the annual fluctuations have decreased and the minimum elevation has not dropped below 773.75 m. A Denil II fishway at the weir provides access to and from the lake for spawning northern pike, yellow perch and walleye (Alta. Envir. n.d.[a]; Envirocon Ltd. 1983).

Water Quality

The water quality of Iosegun Lake was studied by Alberta Environment during the open-water period in 1983 and 1985, and under ice in February of 1984 and 1986 (Alta. Envir. n.d.[b]).

The lake has fresh water that is not as alkaline or as hard as the water in many Alberta lakes (TABLE 3). Calcium and bicarbonate are the dominant ions. In 1983, the lake was thermally stratified from June to August (FIGURE 5). During summer that year, the dissolved oxygen concentration over the bottom sediments fell to low levels. By late August 1983, the dissolved oxygen concentration over the sediments in the deepest part of the lake had declined to 4 mg/L (FIGURE 6). In 1985, the depletion of dissolved oxygen was more pronounced. By July that year, water at depths greater than 10 m was anoxic. Under ice in February 1984, the entire water column remained oxygenated (FIGURE 6), but in February 1986, the water below a depth of 10 m was anoxic.

Iosegun Lake is eutrophic (TABLE 4). In 1983, chlorophyll a concentrations were highest (56 µg/L) at the beginning of August and total phosphorus levels were highest (91 µg/L) at the end of August (FIGURE 7). The elevated concentrations of total phosphorus in the surface water in late summer and fall were most likely the result of phosphorus release by the sediments.

The sewage treatment plant in the town of Fox Creek releases about 0.206 x 106 m3 of treated effluent in spring, and a similar amount in autumn, into an unnamed creek that flows into Iosegun Lake (Pentney 1983). A 4-km stretch of winding creek between the lagoon discharge and the lake, which includes several beaver ponds, a marsh and a slough, probably increases retention time and thus reduces nutrient and bacterial levels in the effluent before it reaches the lake. The overall effect of the effluent on the lake, however, is unknown.

Biological Characteristics


The phytoplankton community in Iosegun Lake was sampled in July 1957 by Fish and Wildlife Division (Hartman 1957) and from May to October in 1983 by Alberta Environment (TABLE 5). In mid-May 1983, cryptophytes (Cryptomonas erosa reflexa, C. ovata and C. rostratiformis) were the dominant group. From June through August, however, blue-green algae (Cyanophyta) formed most of the biomass. In June and July, the most important blue-greens were Anabaena flos-aquae and A. spiroides crassa, but by August, another blue-green, Aphanizomenon flos-aquae, and a diatom (Bacillariophyta), Melosira granulata, were the dominant species. The 1957 study also noted a predominance of blue-green algae in July, primarily Aphanizomenon sp. By mid-October in 1983, diatoms (mostly Stephanodiscus niagarae and Melosira italica) were the major algal group.

Data on the macrophyte community in Iosegun Lake are not available.


A brief survey of the zooplankton and benthic invertebrate communities was conducted in July 1957 by Fish and Wildlife Division (Hartman 1957). No recent data are available.


Iosegun Lake supports populations of lake whitefish, cisco, walleye, northern pike, yellow perch, white sucker, burbot and several minnow species (Hawryluk 1982). In addition, trout-perch, longnose sucker and spottail shiner have been captured near the mouth of Outlet Creek (Envirocon Ltd. 1983). The lake is managed for sport, domestic and commercial fisheries. A few (1 to 3) domestic licences are issued each year, but there are no data for the domestic catch (Alta. For. Ld. Wild. n.d.).

Lake whitefish and cisco are the target species of the commercial fishery. Both species were overexploited during the 1950s and 1960s, and by 1967/68, catches were small. From 1968/69 to 1976/ 77, the fishery was closed. It reopened for 1977/78, but closed for the following two years, and since 1980/81, it has opened only in alternate years. Initially, in 1980/81, the cisco harvest was high (12,600 kg), but it declined to 2,426 kg in 1984/85 and 4,061 kg in 1986/87. Over the same period, the whitefish harvest increased from 2,698 kg in 1980/81 to 6,355 kg in 1986/87 (Alta. For. Ld. Wild. n.d.). In 1988/89, the quotas for these species were 7,000 kg of cisco and 2,500 kg of lake whitefish. The quota is usually taken in one lift. Small amounts of walleye and northern pike are also taken in the commercial fishery. From 1980/81 to 1986/87, the annual walleye catch ranged from 7 to 34 kg and the annual northern pike catch ranged from 108 to 431 kg. The 1988/89 quotas for these species were 100 kg of walleye and 400 kg of northern pike.

The lake was test netted in 1968, 1973, 1976 and 1981 (Hawryluk 1973; 1976; 1982). The species composition of the 1981 catch of 496 fish was 66% cisco, 18% lake whitefish, 14% walleye, 2% northern pike and less than 1% burbot and white sucker. The catch of lake whitefish, cisco, walleye and northern pike increased from 1973 to 1981. Lake whitefish made the greatest gains, from 1.7 fish per 91 m of net (various mesh sizes) in 1973, to 17.9 fish per 91 m of net in 1981. A walleye trapping program in 1985 and 1986 provided a population estimate of 12,908 ± 5,165 mature walleye (Hildebrandt 1986).

Creel surveys were conducted by Fish and Wildlife Division for 8 days from 27 June to 12 August in 1985 and for 35 days from 15 May to 17 August in 1986 (Hawryluk 1986; 1987). In 1986 (TABLE 6), anglers caught an estimated 2,870 northern pike, 2,592 walleye and 12 yellow perch and kept 43% of the northern pike, 87% of the walleye and 58% of the yellow perch. The catch rates for northern pike were very similar in 1985 (0.36/angler-hour) and 1986 (0.35/angler-hour), but the catch rate for walleye declined between 1985 (0.55/angler-hour) and 1986 (0.32/angler-hour). No data are available for the winter sport fishery, but ice fishing is a favourite winter activity at the lake and whitefish and cisco form an important part of the winter angler harvest.


A wide range of wildlife species are found near Iosegun Lake. The lake is an important waterfowl staging area and waterfowl are abundant (Alta. For. Ld. Wild. 1988[b]). Species seen at the lake include Common Loons, grebes, Buffleheads and Goldeneye; a Bald Eagle's nest is located nearby. Black bears are common in the area and grizzly bears have been sighted. The land in the drainage basin is excellent moose habitat. Small mammals present include muskrats, beaver and mink.

M.E. Bradford


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-----. 1986. A creel survey and population estimate in Iosegun Lake (May 17-Aug. 15) 1986. Alta. For. Ld. Wild., Fish Wild. Div. Unpubl. rep., Edmonton.

-----. 1987. A short term creel survey of Iosegun Lake, 1985. Alta. For. Ld. Wild., Fish Wild. Div. Unpubl. rep., Edmonton.

Hildebrandt, D. 1986. Walleye tagging summary, Iosegun Lake May, 1985 and April-May, 1986. Alta. For. Ld. Wild., Fish Wild. Div. Unpubl. rep., Edmonton.

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