|Map Sheets||73L/3, 4|
|Lat / Long||54.1431949, -111.5291870|
|Max depth||9.1 m|
|Mean depth||5.7 m|
|Dr. Basin Area||116 km2|
|Drainage Basin||Beaver River Basin|
|Sport Fish||Yellow Perch, Northern Pike|
|TP x||45 µg/L|
|CHLORO x||22.9 µg/L|
|TDS x||239 mg/L|
Upper and Lower Mann lakes are shallow, sparkling lakes set in the rolling, wooded country northwest of the town of St. Paul. To reach the lakes from St. Paul, take Highway 28 west and north for 32 km to the village of Ashmont, then take Highway 28A east for 5 km. Upper Mann Lake is south of the highway, Lower Mann Lake is north (FIGURE 1). The lakes are in the County of St. Paul.
The lakes were named after Sir Donald Mann (1853-1934), a vice-president of the Canadian Northern Railway Company, which built a rail line close to Upper Mann Lake in the early 1900s (Holmgren and Holmgren 1976). The rail line is now owned by the Canadian National Railway. Before the advent of the railway, the lakes were collectively called Island Lake because they became one large lake with a central island when the water level was high (Owlseye Hist. Soc. 1984).
The best access to Lower Mann Lake is at Lower Mann Lake Provincial Recreation Area at the south end of the lake, just north of Highway 28A (FIGURE 2). This area, which is operated by Alberta Recreation and Parks, provides day-use facilities year-round and camping facilities from the Victoria Day weekend to Thanksgiving Day. Facilities include 70 campsites, pump water, picnic tables and a shelter, a beach, a boat launch and a playground (Alta. Hotel Assoc. 1989). There are no public campgrounds or day-use areas on Upper Mann Lake, but access is available at a boat launch on the northwest shore (FIGURE 2).
Both lakes have been moderately to heavily developed for recreation. There are 197 cottage lots in 8 subdivisions on Lower Mann Lake and 211 lots in 6 subdivisions on Upper Mann Lake; in 1989, more than half of the lots had been developed (Alta. Mun. Aff. 1989). About one-third of the shoreline and the islands in Lower Mann Lake are Crown land, as are the islands and most of the east and southeast shores of Upper Mann Lake (FIGURE 2). A total of 82 ha bordering Upper Mann Lake, including several of the islands and a disjunct area on the south and southeast shore have protective notation, which means that the areas have been proposed as a natural area. The designated land includes excellent wildlife habitat, a beautiful stand of mature white birch trees and islands where pelicans and cormorants rest and feed (Alta. For. Ld. Wild. 1987).
Both lakes are popular for boating and for sport fishing for northern pike and yellow perch. There are no boating regulations specific to either lake (Alta. For. Ld. Wild. 1988). Provincial limits for sport fish catch and possession apply to both lakes and all tributary streams are closed to sport fishing for a designated period in April and May each year (Alta. For. Ld. Wild. 1989).
The water in both lakes is nutrient-rich and dense algal blooms develop by midsummer. The lower lake is greener and supports more areas of nuisance aquatic plant growth than the upper lake.
The drainage basin area of the Mann lakes is large compared to the area of the lakes (Tables 1, 2). However, the southern half of the basin is mostly dead storage and does not contribute runoff to the lakes except when precipitation is exceptionally high, possibly only once or twice a century (Alta. Envir. n.d.[b]).
The drainage basin is gently to moderately rolling with slopes of 5% to 15% (Kocaoglu 1975). It lies within the Dry Mixedwood Subregion of the Boreal Mixedwood Ecoregion (Strong and Leggat 1981). The main soils in the drainage basin are Orthic Gray Luvisols that formed on moderately well-drained, weakly calcareous glacial till (Kocaoglu 1975). The soils in low-lying, poorly drained areas are Orthic Luvic Gleysols. The till in the extended basin area to the southeast of the lakes is more strongly calcareous than in the portion of the basin closer to the lakes and soils are Orthic Gray and Dark Gray Luvisols. The dominant vegetation is trembling aspen with some balsam poplar, white birch and white spruce (Strong and Leggat 1981). Willows are present along the lakeshore and in low-lying areas around reed/grass meadows (Alta. For. Ld. Wild. 1987). Almost two-thirds of the basin has been cleared for agriculture, primarily grazing and forage production (FIGURE 1).
Both Upper and Lower Mann lakes are very irregularly shaped and are dotted with numerous islands. Upper Mann is the deeper of the two lakes; its maximum depth is 9.1 m, versus 6.1 m for the lower lake. The basin of the upper lake slopes more steeply than that of the lower lake (FIGURE 2).
The water level of Upper Mann Lake has been monitored since 1962 (FIGURE 3) and that of Lower Mann has been monitored since 1973 (FIGURE 4). The water levels in both lakes were high in 1979 and then steadily dropped to historic low levels in late 1988. Over this period, both lakes declined by 1.3 m. This drop in lake level reduced the area of Upper Mann Lake by only 7% (FIGURE 5), but the area of Lower Mann Lake was reduced by approximately 15% (FIGURE 6). There is no control structure on either Upper or Lower Mann Lake, but the water level in the two lakes is controlled to some extent by a weir on Greenstreet Lake, which is immediately downstream of Lower Mann Lake. The weir was built in 1983 and is operated by Alberta Forestry, Lands and Wildlife. The weir elevation is 615.85 m. As of 1989, drought conditions since the weir was completed had kept water levels lower than this elevation.
The residence time of water in Lower Mann Lake is much shorter (21 years) than in Upper Mann Lake (69 years, TABLE 2). These estimates do not consider groundwater inflow or outflow, which is probably significant in maintaining lake levels.
The water quality of Upper and Lower Mann lakes was sampled by Alberta Environment on 6 March 1979 and on 16 August 1983. Upper Mann Lake was also sampled four times in 1984 for nutrients, chlorophyll a, temperature and dissolved oxygen (Alta. Envir. n.d.[a]).
Both lakes have well-buffered, fresh water (TABLE 3). The limited sampling has not detected thermal stratification in either lake, except in mid-June 1984, when a 20°C difference in temperature from top to bottom was found in Upper Mann Lake (FIGURE 7, 8). In both lakes, dissolved oxygen in the water near the sediment was depleted during summer; in Upper Mann Lake, the water near the bottom was anoxic by mid-August 1983. By October 1983, however, the lake had mixed and the dissolved oxygen concentration near the substrate had increased to 10 mg/L. In the winter of 1978/79, water at the bottom of both lakes was anoxic by 6 March. Severe winterkills of pike and perch are recorded in Lower Mann Lake in most years. In Upper Mann Lake, a severe winterkill occurs occasionally and partial winterkills occur approximately every five years (Sullivan 1989).
The few data collected indicate that both Lower and Upper Mann lakes are hyper-eutrophic (TABLE 4, FIGURE 9). In Upper Mann Lake, the total phosphorus concentration in the euphotic zone increased to a peak of 113 mg/L on 16 August 1984, likely because phosphorus was released from anoxic sediments. Chlorophyll a concentrations followed the total phosphorus concentrations and reached a peak of 51 µg/L (FIGURE 9).
The density of algae in both Upper and Lower Mann lakes is so high that it interferes with recreational use. In summer, blue-green algae cause both visual and odour problems (Alta. Mun. Aff. 1989). The phytoplankton in both lakes was sampled on 16 August 1983 (Alta. Envir. n.d.[a]). In Upper Mann Lake, 85% of the total algal biomass (7.06 mg/L) was blue-green algae (Cyanophyta), mostly Anabaena flos-aquae and Microcystis aeruginosa. In Lower Mann Lake, 69% of the total biomass (10.91 mg/L) was blue-green algae, mostly Microcystis aeruginosa, Lyngbya Birgei and Anabaena flos-aquae. Upper Mann Lake also supported a small biomass of the dinoflagellate (Pyrrhophyta) Ceratium hirundinella, and two species of Cryptophyta, mostly Cryptomonas erosa reflexa. Lower Mann Lake differed from Upper Mann Lake in that the algal community in the lower lake included 19% diatoms (Bacillariophyta: mostly Stephanodiscus niagarae), compared with less than 1% diatoms in the upper lake. Cryptophytes and pyrrhophytes were similar in abundance in both lakes.
The phytoplankton in Upper Mann Lake was also sampled on 21 June, 14 August and 9 October in 1984. In June, 60% of the total biomass (0.41 mg/L) was cryptophytes and 30% was diatoms. In August, 55% of the total biomass (16.7 mg/L) was blue-greens and 39% was Ceratium hirundinella. By October, the biomass had decreased to 9.3 mg/L, and was composed of 67% diatoms and 27% blue-greens.
Macrophytes are a widespread nuisance to boaters in Lower Mann Lake and present problems in shallow, sheltered areas of Upper Mann Lake (Sullivan 1989). In Upper Mann Lake, in August 1986, submergent macrophytes - mostly Ceratophyllum demersum, but also some star duckweed (Lemna trisulca), white-stem pondweed (Potamogeton praelongus) and northern watermilfoil (Myriophyllum exalbescens) - were recorded to depths of 2.9 m (Chambers and Prepas n.d.; 1988). In 1988, areas of dense emergent and submergent growth in both lakes were mapped by Alberta Municipal Affairs (FIGURE 10). In Upper Mann Lake, the east and south shores supported dense communities of emergent and submergent plants, and the north and west shores were relatively weed-free except in sheltered bays where northern watermilfoil grew abundantly. In Lower Mann Lake, the north and east shores supported dense areas of cattails (Typha sp.) and bulrushes (Scirpus sp.), and passage along the eastern shore of the large island is often blocked. The entire northern portion of the lower lake supports dense submergent growth.
There are no data on the invertebrates in either of the Mann lakes.
The Mann lakes support an erratically popular sport fishery for northern pike and yellow perch. Walleye were stocked by Fish and Wildlife Division in Upper Mann Lake in 1960 and 1984, but there has been only one unconfirmed report of a walleye being caught. Severe winterkills occur in Upper Mann Lake in some years and partial winterkills occur approximately one year in five. Severe winterkills occur in Lower Mann Lake in most years; the lake is repopulated by pike and perch that migrate from Upper Mann Lake through the culverts under Highway 28A. Winterkills keep the size of the perch and pike population low, and high nutrient levels promote abundant food production; therefore, the growth rates of surviving fish are rapid. In winters when the lakes do not winterkill, the pike and perch are large and easily caught, and anglers flock to the lakes. In other years, angling success is negligible (Sullivan 1989).
Both lakes were fished commercially for a few years during the 1940s. A total of three licences were issued for Upper Mann Lake and a total of 18,000 kg of pike were harvested between 1944 and 1947. In Lower Mann Lake, a total of 19,000 kg of pike and 11,500 kg of perch were harvested between 1944 and 1949 (Alta. Rec. Parks Wild. 1976).
Both lakes provide good habitat for waterfowl nesting. Resting and feeding cormorants and pelicans are often seen on or near the islands in Upper Mann Lake.
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.
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 Hotel Association. 1989. Alberta campground guide 1989. Prep. for Travel Alta., Edmonton.
Alberta Municipal Affairs. 1989. Upper and Lower Mann lakes management study. Plan. Div., Plan. Br., 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. n.d. Univ. Alta ., Dept. Zool. Unpubl. data, Edmonton.
-----. 1988. Underwater spectral attenuation and its effect on the maximum depth of angiosperm colonization. Can. J. Fish. Aquat. Sci. 45:1010-1017.
Energy, Mines and Resources Canada. 1971, 1978. National topographic series 1:50000 73L/3 (1971), 73L/4 (1978). Surv. Map. Br., Ottawa.
Environment Canada. 1982. Canadian climate normals, Vol. 7: Bright sunshine (1951-1980). Prep. by Atm. Envir. Serv. Supply Serv. Can., Ottawa.
Holmgren, E.J. and P.M. Holmgren. 1976. Over 2000 place names of Alberta. 3rd ed. West. Producer Prairie Books, Saskatoon.
Kocaoglu, S.S. 1975. Reconnaissance soil survey of the Sand River area. Alta. Soil Surv. Rep. No. 34, Univ. Alta. Bull. No. SS-15, Alta. Inst. Pedol. Rep. No. S-74-34 1975. Univ. Alta., Edmonton.
Owlseye Historical Society. 1984. An era in review-A history of Owlseye-Ashmont, Abilene, Boscombe, Cork, Boyne Lake, Anning and area. Owlseye Hist. Soc., St. Paul.
Strong, W.L. and K.R. Leggat. 1981. Ecoregions of Alberta. Alta. En. Nat. Resour., Resour. Eval. Plan. Div., Edmonton.
Sullivan, M. 1989. Alta. For. Ld. Wild., Fish Wild. Div., St. Paul. Pers. comm.