|Lat / Long||53.1333333, -113.3500000|
|Max depth||5.5 m|
|Mean depth||3.5 m|
|Dr. Basin Area||1250 km2|
|Drainage Basin||Battle River Basin|
|Sport Fish||Yellow Perch, Northen Pike|
|TP x||176 µg/L|
|CHLORO x||43.5 µg/L|
|TDS x||288 mg/L|
Coal Lake is a long, sinuous lake located approximately 60 km southeast of the city of Edmonton. Most of the lake is in the County of Wetaskiwin, but the northern portion is in the County of Leduc. Coal Lake lies in a portion of the glacial meltwater channel that drained glacial Lake Edmonton after the last ice age about 12,000 years ago. Beginning east of Nisku, the channel can be traced as it winds southeastward through a chain of lakes-Saunders, Ord, three unnamed ephemeral lakes, Coal and Driedmeat. Coal Lake is attractively bordered by treed valley walls rising 45 m above the lake. Access to the water is available at Alberta Environment day-use areas at each end of the lake. The southern day-use area can be reached by driving west from the city of Wetaskiwin on Highway 13 for 13 km and turning north onto Secondary Road 822 (FIGURE 1) just west of the hamlet of Gwynne. The northern day-use area is located where Secondary Road 616 (Cloverlawn Road) crosses the lake (FIGURE 2). Both day-use areas include boat launches, parking areas and picnic tables. There is no campground at Coal Lake.
Coal Lake was named in 1892 by J.D.A. Fitzpatrick, a Dominion Land Surveyor, for the coal beds present in many places along the northeast shore (Millet Dist. Hist. Soc. 1978). It is likely the same lake that is labelled "Long Lake" on the Palliser map of 1859 (Holmgren and Holmgren 1976). Despite the obvious beds of coal, there has never been any commercial mining near the lake. However, local farmers mined small quantities of coal along the shore until the early 1950s.
Coal Lake has been used as a municipal water supply by the City of Wetaskiwin since 1968 (City Wetaskiwin n.d.). Prior to the construction of a dam in 1972, the lake was much shallower, with a maximum depth of 2.5 m. In dry years, algal blooms in the lake caused intolerable taste and "curious colour" in the city drinking water (Battle R. Reg. Plan. Commis. 1974). In 1972, Alberta Environment built a dam across the valley 100 m downstream of the natural sill; this rerouted Pipestone Creek to flow into Coal Lake (FIGURE 2). The lake surface is now 3 m higher, the water quality has improved and the lake is a reliable source of water for Wetaskiwin. The lake still supports a dense blue-green algal bloom through most of the summer.
Year-round sport fishing for northern pike is popular at Coal Lake. There are no sport fishing regulations specific to the lake, but general provincial regulations apply (Alta. For. Ld. Wild. 1989). The lake is also popular for power boating and snowmobiling. General federal boating regulations apply to the lake, but there are no specific restrictions (Alta. For. Ld. Wild. 1988). A hiking trail developed by the Waskahegan Trail Association follows the western shore (Battle R. Reg. Plan. Commis. 1974).
The drainage basin of Coal Lake was about 100 km2 prior to dam construction in 1972. Since 1972, Pipestone Creek has flowed into Coal Lake and the watershed now includes the Pipestone-Bigstone Creek drainage basin and totals 1,250 km2 (TABLE 1, FIGURE 1). Water flows out of Coal Lake via Pipestone Creek to the Battle River, 10 km to the southeast.
The drainage basin is located in the Aspen Parkland Ecoregion (Strong and Leggat 1981). Almost all of the land above the top of the valley has been cleared and is farmed intensively for grain and livestock production (Battle R. Reg. Plan. Commis. 1974). The terrain outside of the valley is level or undulating to gently rolling. Within the glacial channel that extends upstream and downstream of Coal Lake, some of the valley floor is leased for hay production or grazing and the valley sides support trembling aspen, balsam poplar, willows and shrubs. The dominant soils are Solonetzic Black Chernozemics on the uplands and Solodized Solonetz on the valley floor (Bowser et al. 1947). The valley walls are fairly steep and erode easily if the vegetation is removed (Battle R. Reg. Plan. Commis. 1974). The tributary creeks have carved deep coulees, and alluvial fans have formed in the lake at the inlets.
There are many farms and several small population centres within the drainage basin, including the hamlets of Gwynne, Bright View and Usona and the village of Millet. The city of Wetaskiwin is only 10 km southwest of the lake but is outside the drainage basin. All of the land bordering Coal Lake is Crown land (FIGURE 2).
Coal Lake is 18-km long, but only 0.7-km wide at its widest point. The lake has a steeply sloping bottom (FIGURE 2). The substrate is primarily firm sand and clay to a water depth of 2.0 m; in water deeper than 2 m, the substrate is soft flocculent mud (Integrated Envir. Sci. Inc. 1984). When the lake is at an elevation of 703 m, approximately 20% of the lake is less than 2.0-m deep (FIGURE 3), which is the limit of dense aquatic plant growth. Since 1972, the lake level has been regulated by an earthen embankment and dam with a low-level riparian outlet and a concrete overflow spillway (TABLE 2). This dam raised the lake level by 3 m. From 1974 to 1986 the level has fluctuated 1.2 m (FIGURE 4). The average annual volume of water that passes through the lake is sufficient to exchange the volume every year (TABLE 2), but because Pipestone Creek flows into the lake very near the outlet, most of the water is "short-circuited" and the effective residence time is likely very long.
Alberta Environment built the dam on Coal Lake to meet two objectives: to ensure an adequate supply of good quality water for Wetaskiwin (Battle R. Reg. Plan. Commis. 1974) and to create a reservoir to augment flows in the Battle River in times of drought (Alta. Envir. n.d.[a]). The Wetaskiwin diversion intake is on the southwest shore of the lake. In 1986, the city withdrew 10.3 x 106 m3 of water (City Wetaskiwin n.d.). The capacity for flow augmentation has been used only twice: in the summer of 1977 and in the winter of 1985/86.
Coal Lake was sampled by Alberta Environment from 1982 to 1985 (Alta. Envir. n.d.[b]; n.d.[c]; Sloman 1984).
Coal Lake is a well-buffered, freshwater lake (total dissolved solids average 273 mg/L, TABLE 3). The dominant ions are bicarbonate and sodium. The lake is shallow and is likely thermally stratified only occasionally in summer (FIGURE 5). It may become more strongly stratified in areas of dense macrophyte growth where wind-induced currents are attenuated. In late July 1984, the dissolved oxygen concentration declined to 1.6 mg/L at the bottom while it remained at 8.0 mg/L at the surface (FIGURE 6). The oxygen depletion was likely due to the decay of a dense algal bloom in the lake.
In winter, dissolved oxygen levels near the dam were only 4.0 mg/L at the surface and 2.0 mg/L at the bottom by mid-February in both 1983 and 1986 (FIGURE 6). The northern end of the lake just south of Secondary Road 616 had fairly high dissolved oxygen concentrations all winter. On 23 February 1983, for example, concentrations were 8.1 mg/L at the surface and 5.8 mg/L at the bottom. The water remained open near this site all winter of both years.
Coal Lake is hyper-eutrophic and supports a conspicuous, dense algal bloom during most of the summer (TABLE 4). The mean open-water total phosphorus concentration is higher (176 µg/L) than that recorded in 36 other lakes that have been similarly studied by Alberta Environment (Alta. Envir. n.d.[b]). The total phosphorus concentration in Coal Lake increased over the open-water period from less than 50 µg/L in May to a maximum of 342 µg/L in late August (FIGURE 7). This suggests that phosphorus was released from the sediments, as occurs in many central Alberta lakes.
The species composition and biomass of the phytoplankton community was examined by Alberta Environment in 1984 and in 1985 (TABLE 5). In 1984, there was a dense bloom of blue-green algae (Cyanophyta) dominated by Aphanizomenon flos-aquae through June and July. This was followed in September by a strong bloom of diatoms (Bacillariophyta) dominated by Stephanodiscus niagarae. In comparison, data from 1985 suggest that a blue-green bloom occurred from June to late August, dominated first by Anabaena flos-aquae in June, then by Microcystis aeruginosa. The diatom bloom that year, as in 1984, was dominated by Stephanodiscus niagarae; it peaked in August and continued through September. The phytoplankton was sampled once under ice-cover, on 20 February 1985. At that time, algal biomass was 0.3 mg/L; diatoms (Stephanodiscus niagarae) and cryptophytes (Cryptomonas rostratiformis) were codominant.
Macrophytes in Coal Lake were mapped in detail for Alberta Environment in 1984 (TABLE 6). Emergent species were most conspicuous at the southern end of the lake and in the northern section. In the main portion of the lake, cattle grazing and active soil slumping limited emergent growth to small pockets of Carex spp. Submergent species covered 112.6 ha, or 11% of the lake's area. The dominant species were pondweeds (Potamogeton richardsonii, P. vaginatus and P. pectinatus). Submergent macrophytes grew densely in a narrow band, 5- to 20-m wide, along almost the entire shoreline. The plants were generally limited to water 1.5- to 2.0-m deep and grew up to the surface. More extensive and widespread growth was found at both ends of the lake and near the inlet streams.
There are no data on the invertebrates in Coal Lake.
Prior to dam construction, Coal Lake supported few sport fish because of severe winterkills (Battle R. Reg. Plan. Commis. 1974). It now supports a popular local sport fishery for northern pike, and was stocked with yellow perch by Fish and Wildlife Division in 1983, 1984 and 1985 (Alta. En. Nat. Resour. 1983-1985). In May 1984, Fish and Wildlife Division set three gangs of test nets for 24 hours and caught 602 white suckers, 234 northern pike and 14 yellow perch (Alta. For. Ld. Wild. n.d.). Migration of fish into Coal Lake from the Battle River is now blocked by the Coal Lake dam, but fish can still pass downstream over the dam. Pipestone Creek immediately downstream of Coal Lake is a primary spawning area for northern pike and white suckers from the Battle River (Fernet et al. 1985). Forage fish in the lake include lake chub, emerald shiner, longnose dace and brook stickleback (Fernet et al. 1985).
The best areas of Coal Lake for waterfowl production are the shallow northern portion and the area near the dam at the south end. The shore on the rest of the lake is too steep to provide good nesting habitat (Boyko 1987). Large numbers of ducks and Common Loons feed on the lake and numerous waterfowl stop there on migration. A nesting colony of Great Blue Herons is located on the outlet creek. Muskrats and beaver are frequently seen.
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-----. n.d.[b]. Envir. Assess. Div., Envir. Qlty. Monit. Br. Unpubl. data, Edmonton.
-----. n.d.[c]. Plan. Div., Plan. Serv. Br. Unpubl. data, Edmonton.
-----. n.d.[d]. Tech. Serv. Div., Hydrol. Br. Unpubl. data, Edmonton.
-----. n.d.[e]. Tech. Serv. Div., Surv. Br. Unpubl. data, Edmonton.
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-----. 1988. Boating in Alberta. Fish Wild. Div., Edmonton.
-----. 1989. Guide to sportfishing. Fish Wild. Div., Edmonton.
Alberta Research Council. 1972. Geological map of Alberta. Nat. Resour. Div., Alta. Geol. Surv., Edmonton.
Battle River Regional Planning Commission. 1974. Coal Lake-A study of conflicting uses. Prep. for Co. Wetaskiwin, Wetaskiwin.
Bowser, W.E., R.L. Erdman, F.A. Wyatt and J.D. Newton. 1947. Soil survey of Peace Hills sheet. Alta. Soil Surv. Rep. No. 14, Univ. Alta. Bull. No. 48. Univ. Alta., Edmonton.
Boyko, D. 1987. Alta. For. Ld. Wild., Fish Wild. Div., Wetaskiwin Dist. Office. Pers. comm.
City of Wetaskiwin. n.d. Eng. Dept. Unpubl. data, Wetaskiwin.
Energy, Mines and Resources Canada. 1970, 1983. National topographic series 1:250 000 83A (1970), 83H (1983). Surv. Map. Br., Ottawa.
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-----. 1982. Canadian climate normals, Vol. 7: Bright sunshine (1951-1980). Prep. by Atm. Envir. Serv. Supply Serv. Can., Ottawa.
Fernet, D.A., G.A. Ash and S.M. Matkowski. 1985. Investigations of the Battle River fishery relative to the potential effects of flow augmentation. Prep. for Alta. Envir., Plan. Div. by Envir. Mgt. Assoc., Calgary and R.L. & L. Envir. Serv. Ltd., Edmonton.
Holmgren, E.J. and P.M. Holmgren. 1976. Over 2000 place names of Alberta. 3rd ed. West. Producer Prairie Books, Saskatoon.
Integrated Environmental Sciences Inc. 1984. Aquatic macrophyte surveys of Coal Lake, Driedmeat Lake and the Battle Reservoir. Prep. for Alta. Envir., Plan. Div., Edmonton.
Millet and District Historical Society. 1978. Tales and trails of Millet, Vol. 1. Millet Dist. Hist. Soc., Millet.
Sloman, K.W. 1984. Dissolved oxygen in the Battle River system, winter 1982/83. Alta. Envir., Plan. Div., Edmonton.
Strong, W.L. and K.R. Leggat. 1981. Ecoregions of Alberta. Alta. En. Nat. Resour., Resour. Eval. Plan. Div., Edmonton.