|Lat / Long||53.4500000, -118.2666667|
|Max depth||27.8 m|
|Mean depth||12.1 m|
|Dr. Basin Area||348 km2|
|Drainage Basin||Athabasca River Basin|
|Sport Fish||Bull Trout, Mountain Whitefish, Northern Pike, Lake Trout|
|Trophic Status||No Data|
|TP x||No Data µg/L|
|CHLORO x||No Data µg/L|
|TDS x||No Data mg/L|
Rock Lake is a small, deep, very attractive lake situated in the front ranges of the Rocky Mountains. It is located in Improvement District No. 14, 75 km northwest of the town of Hinton, 4 km north of Jasper National Park and 1 km east of Willmore Wilderness Park (FIGURE 1). Well-defined trails into these areas begin near Rock Lake, so the lake is an excellent staging area for back-country hiking and horseback trips. To reach the lake from Hinton, take Highway 16 southwest for 8 km to its junction with Highway 40. Travel north for 37 km on Highway 40, then travel west for 32 km on an all-season gravel road that leads directly into Rock Lake Forest Recreation Area. The road usually is not ploughed to the lake in winter.
The lake's name originates from an Indian legend about a banished Stoney Medicine Man who kidnapped a Dog Rib maiden by changing her into a dog. Before he attempted to rejoin his tribe, the Medicine Man returned the maiden to human form but stole her power of speech. His tribe thought him clever when he told them of his "rescue" of the maiden, and they allowed him to stay. Soon after, a Dog Rib warrior - the maiden's betrothed - entered the camp and tricked the Medicine Man into returning the maiden's speech. After she told the true story, the Stoney chief ordered the Medicine Man bound and weighted with a heavy rock, then thrown into the lake (Alta. Cult. Multicult. n.d.).
Rock Lake Forest Recreation Area is an Alberta Forest Service campground located on the northern and eastern shores of the lake. It is open from 15 May to 15 September and offers 86 campsites, 11 remote tenting sites, 18 picnic sites, 2 picnic shelters, pump water, 2 boat launches and a pier. Back-country horseback trips can be staged from the northern end of the recreation area, where there is limited grazing and a place to park vehicles and horse trailers.
The main recreational activities at Rock Lake are camping and sport fishing. The unspoiled surroundings, private campsites and mountain setting make the lake a popular destination, especially for weekend campers from the Edmonton area. No water skiing or towing of surfboards is allowed on the lake (Alta. For. Ld. Wild. 1988). The water is clear and aquatic vegetation is minimal. The main sport fish species are lake trout, mountain whitefish and northern pike; bull trout and rainbow trout are caught less frequently. Fishing for bait fish and the use of bait fish in Rock Lake are not allowed (Alta. For. Ld. Wild. 1989).
Rock Lake's drainage basin covers a large area that is more than 160 times the size of the lake (Tables 1, 2). It extends far back into the mountains and reaches altitudes greater than 2,700 m (FIGURE 1). Except for the land immediately surrounding the lake, the watershed is undeveloped and lies entirely within Jasper National Park and Willmore Wilderness Park. The lake basin was formed during the retreat of the Wisconsin glaciers about 12,000 years ago, and continuous erosion and mountain uplift have contributed to the topography of the area. Three permanent streams enter the lake. Rock Creek, which flows into the western side, provides the majority of the inflow (Lane 1969). The outlet is a fork of the Wildhay River, which eventually drains into the Athabasca River.
The land close to the lake is part of the Subalpine Ecoregion (Strong and Leggat 1981). The topography in this area is characterized by a broad, open meadow west of the lake, a forested mountain slope near the southern shore and high, open hillsides north of the lake (Miller and Paetz 1952). The main soils in the Subalpine Ecoregion are Eutric Brunisols, and the dominant trees are Engelmann spruce and lodgepole pine. Limber pine, black and white spruce, and Douglas fir are less common and deciduous species such as trembling aspen are present only on the warmest sites.
The Alpine Ecoregion is situated above the forest-line, which is located at elevations of approximately 1,980 to 2,135 m (Strong and Leggat 1981). Above the forest-line, the contiguous forest stops and isolated stands of trees begin. Soils are poorly developed, and vegetation varies with the substrate and amount of protection from the harsh environment. Glaciers are bare of vegetation, whereas rock fields support crustose lichens, most commonly Rhizocarpon spp. and Omphaldiscus spp. Alpine fir, Engelmann spruce, whitebark pine and alpine larch are the common trees. They are deformed and stunted and grow only on protected sites. Willows grow on Gleysolic or Regosolic soils in wetter areas and heath (Phyllodoce spp.), Kobresia spp. and fescue communities are present on moderately well-drained Brunisolic soils.
Rock Lake is a small water body that is relatively deep for its size (TABLE 2, FIGURE 2). The lake's maximum depth of 27.8 m is located in the centre of the single basin. The northern and southern shores are rocky and the sides of the basin slope steeply, whereas the eastern and western ends are quite shallow. The bottom substrate in most areas, to a depth of approximately 10 m, is rich in organic matter, with numerous sand and gravel bars. At the eastern end the bottom is sandy (Miller and Paetz 1952; Lane 1969).
The elevation of Rock Lake was recorded once in each of 1968, 1971, 1972 and 1973, and has been monitored regularly since 1974 (FIGURE 3). The difference between the historic maximum (1,387.82 m) and minimum (1,386.92 m) observed levels is 0.90 m. This range in lake levels would result in a fluctuation of about 0.3 km2 of the lake's area (FIGURE 4).
Water quality data for Rock Lake are limited. Fish and Wildlife Division conducted brief surveys in 1952 and 1968 (Miller and Paetz 1952; Lane 1969). Rock Lake has well-buffered, fresh water. In 1968, the ice left the lake on 30 May. By early June, when the water was very turbid because of turnover and spring runoff, the Secchi transparency was only 0.8 m. By August, the Secchi depth had increased to 4.1 m.
Rock Lake is quite deep, but the water column does not become thermally stratified until late in the ice-free period. In 1968, the lake was isothermal in June but a thermocline was present in early August (FIGURE 5). After turnover in June, the dissolved oxygen concentration was only 6 mg/L throughout the water column (FIGURE 5). By August, the dissolved oxygen concentration in water near the sediments had declined slightly to 5 mg/L.
Data to determine the trophic status of Rock Lake are not available, but it is likely that the lake is relatively unproductive.
No quantitative data are available for the plant community. Net plankton samples were taken in August 1952 and June and August 1968 (Miller and Paetz 1952; Lane 1969). Both studies reported very low concentrations of algae. In 1968, aquatic macrophytes grew densely at the shallow southwest end of the lake, but density was quite low in other shallow areas. The most common submergent plants were northern watermilfoil (Myriophyllum exalbescens) and pondweeds (Potamogeton spp.).
No quantitative data are available for the zooplankton community. Net plankton samples were taken in 1952 and 1968 and relative abundance was determined (Miller and Paetz 1952; Lane 1969). Benthic invertebrates were also sampled during these studies. In 1968, the average standing crop of benthos was estimated to be 8.7 kg/ha (dry weight), which is a relatively high biomass for an unproductive lake. Numerically, 37% of the organisms were midge larvae (Chironomidae), 31% were aquatic earthworms (Oligochaeta) and 27% were molluscs (Sphaeriidae). Most organisms were found at depths of less than 10 m. Only midges, molluscs and aquatic earthworms were found at greater depths; 72% of the worms were found between 20 and 27 m.
Eight species of fish have been caught in Rock Lake: mountain whitefish, lake trout, bull trout, northern pike, longnose sucker, burbot, spoonhead sculpin and finescale dace (Miller and Paetz 1952; Lane 1969; Hunt 1989). Other species - white sucker, rainbow trout and yellow perch - have been reported but not confirmed. In 1983, 1986 and 1987 the lake was stocked with 7,000 lake trout (Alta. En. Nat. Resour. 1983; Alta. For. Ld. Wild. 1986; 1987). Rock Lake is managed as a recreational fishery, and there is no commercial or domestic fishery present.
The most abundant of five species caught in a 1968 test netting were primarily mountain whitefish (63%) and secondarily lake trout (27%), whereas in a 1979 creel survey, lake trout accounted for 47% of the catch and mountain whitefish accounted for 37% (Lane 1969; Mentz 1980). The largest whitefish taken in 1968 weighed almost 1.5 kg and was estimated to be 16 years old. The size-at-age of 5-year-old Rock Lake mountain whitefish in 1968 (29.5 cm) was considerably greater than whitefish of the same age from Crowsnest Lake (21.3 cm), Lake Louise (18.0 cm) and Waterton Lake (22.6 cm).
Most angling at Rock Lake takes place during the summer months, with peak pressure from 15 August to 15 September (Hunt 1989). Winter angling pressure is low because access is difficult. During 1979, it was estimated from creel survey data that 1,583 anglers visited the lake from 1 June to 21 September and spent 4,538 hours fishing (TABLE 3). The preferred catches were mountain whitefish and lake trout. Approximately 90% of the anglers interviewed thought that catch rates were poor and the fish were small. Most anglers (75%) travelled 320-480 km to visit the lake; many of these people came from the Edmonton area (Mentz 1980). Lake trout spawning areas in Rock Lake have not been confirmed, but preliminary surveys in 1977 and 1978 found only marginal spawning habitat. This suggests that suitable spawning habitat could be a limiting factor to lake trout production. The success of lake trout stocking in the 1980s had not been evaluated by 1989, but reports by Fish and Wildlife Division staff suggested that there had been no improvement in the fishery. In 1989, a lake trout management proposal for Rock Lake was completed, and the recommendations were being reviewed (Hunt 1989).
Information about the wildlife at Rock Lake is limited. The lake is not extensively used by waterfowl because of late ice breakup in spring and early freeze-up in fall. Waterfowl that have been sighted on the lake include Mallards, Common Goldeneye and Canada Geese. Elk are the most numerous ungulate in the area. They use the hills north of the lake as a winter range, as do moose, mule deer and white-tailed deer. Bighorn sheep and mountain goats inhabit Willmore Wilderness Park, and black bears, grizzlies and wolverines are present in the drainage basin (Smith 1989).
Alberta Culture and Multiculturalism. n.d. Hist. Resour. Div., Hist. Sites Serv. Unpubl. data, Edmonton.
Alberta Energy and Natural Resources. 1983. Fish planting list. Fish Wild. Div., Edmonton.
Alberta Environment. n.d.[a]. Tech. Serv. Div., Hydrol. Br. Unpubl. data, Edmonton.
-----. n.d.[b]. Tech. Serv. Div., Surv. Br. Unpubl. data, Edmonton.
Alberta Forestry, Lands and Wildlife. 1986, 1987. Fish planting list. Fish Wild. Div., Edmonton.
-----. 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.
Energy, Mines and Resources Canada. 1981. National topographic series 1:50000 83E/8 (1981). 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.
Government of Canada. 1960. National topographic series 1:50 000 83E/7 E & W. Army Surv. Establishment, R.C.E., Ottawa.
-----. 1962. National topographic series 1:50 000 83E/10 E & W. Dept. Mines Tech. Surv., Surv. Map. Br., Ottawa.
Hunt, C. 1989. Lake trout management proposal for Rock Lake. Alta. For. Ld. Wild., Fish Wild. Div. Unpubl. rep., Edson.
Lane, C.B. 1969. The limnology and fishery management of Rock Lake, Alberta. Alta. Ld. For., Fish Wild. Div., Surv. Rep. No. 8, Edmonton.
Mentz, E. 1980. Rock Lake creel survey, June 1 to September 21, 1979. Alta. En. Nat. Resour., Fish Wild. Div. Unpubl. rep., Edmonton.
Miller, R.B. and M.J. Paetz. 1953. Preliminary biological surveys of Alberta watersheds, Vol. II: 1950-1952. Alta. Ld. For., Fish Wild. Div., Edmonton.
Smith, K. 1989. Alta. For. Ld. Wild., Fish Wild. Div., Edson. Pers. comm.
Strong, W.L. and K.R. Leggat. 1981. Ecoregions of Alberta. Alta. En. Nat. Resour., Resour. Eval. Plan. Div., Edmonton.