Water Survey of Canada - 05AF
History and Overview
The Pakowki Lake sub-watershed of the South Saskatchewan River Basin lies north of Milk River and south-west of Cypress Hills in a long narrow band stretching east from the town of Raymond in the County of Warner to the hamlet of Manyberries in the County of Forty Mile.
The ecology and geography of the sub-watershed are similar to others within the region – a gently rolling landscape of dry mixed-grass prairie carved by occasionally deep coulees. The hydrology of the sub-watershed however is quite different from the others that make up the South Saskatchewan River Basin within Alberta; it is a large internal drainage basin – a closed hydrologic system also known as a non-contributing, closed or endorheic basin.
Low elevations within closed basins are usually occupied by salty lakes or salt pans that receive and retain water but do not discharge it like typical drainage basins through an out-flowing stream. If you look at a map of Alberta, Pakowki Lake, from which the sub-watershed gets its name, stands out as the largest water body in the south and at its maximum the lake can cover over 123 square kilometres. Maps can be deceptive though; Pakowki is an ephemeral or intermittent lake and most years open water covers a much smaller area. Because the lake sits in a shallow dish of alkali substrate the addition of a relatively small amount of water can dramatically increase the surface area; the mean depth of the lake however is only 1.2 metres.
Any rain or other precipitation that falls within an internal drainage basin either immediately seeps into the ground or evaporates, or it flows as surface water to an inland location where it then seeps into the ground or evaporates. The only permanent surface water channel that feeds into Pakowki Lake is Etzikom Coulee – a large glacial spillway that collects water from across the sub-watershed – but the lake is also fed by smaller, intermittent streams and coulees including Irrigation Creek, Erickson Coulee, Ketchum Creek, Canal Creek, Bond Coulee, and Bryant Coulee. Pakowki Lake does overflow in times of extreme flooding, discharging through a channel which flows into the Milk River six kilometres to the south.
There are several other large water bodies within the sub-basin including the Milk River Ridge Reservoir, an artificial lake developed along Nine Mile Coulee south-east of Lethbridge, and Crow Indian Lake, a swollen section of Etzikom Coulee. Etzikom Coulee itself is a fairly dramatic feature of the landscape; it begins at the Milk River Ridge Reservoir and winds its way north and then southeast for 110 kilometres carving a canyon up to 40 metres deep before it ends south of the village of Etzikom at Pakowki Lake.
Smaller but otherwise notable water bodies within the sub-basin include Stirling Lake located just north of Stirling, the Tyrell-Rush Wetland Complex north-west of Warner, and Raymond Reservoir. Stirling Lake, which is fed by Nine Mile Coulee and outflows to Etzikom Coulee, is also referred to as Michelson Marsh and it is well known for its wide variety of bird species. The Tyrell-Rush Complex was the first Wetlands for Tomorrow project built in Alberta. Funds were contributed by Alberta Environment, Ducks Unlimited (Canada) and Fish and Wildlife, and it was built in cooperation with the County of Warner and the St. Mary River Irrigation District (SMRID). Canals and structures were built to stabilize water levels in both Tyrell Lake and Rush Lake, and in a large marshland south of Rush Lake. The extensive wetland area that was created provides valuable waterfowl habitat in a drought-prone area and it benefits agriculture because the project includes a drainage system that moves excess runoff from farmland into the Rush Lake drain, which then conveys the water to Etzikom Coulee. Raymond Reservoir lies within the Pakowki sub-basin although it is actually part of the Raymond Irrigation District which receives water from the St. Mary River. The reservoir is fairly unique in that it has a small automatic hydro-electric plant that operates during the irrigation season from April to October. The SMRID supports waterfowl habitat around the reservoir in partnership with Ducks Unlimited.
There are several possible origins of the name Pakowki. One source states that in 1855, a traveller named James Doty passed by Pakowki Lake while looking for the Blackfoot. He noted in his journal that although the water was clear, it had an offensive odour of hydrogen sulphide caused by the lack of outflow; Pakowki is a Blackfoot word that can be loosely translated as “bad water.” Another aboriginal name for the lake was pah-kan-kee, which translates as “unlucky water,” and C. E. Wolff, the Dominion Land Surveyor who was in the area in 1883 recorded the name as Pakoghkee. Place Names also suggests the name might mean “rolling hills.”
Land use within the Pakowki Lake sub-basin is that of the region in general; extensive areas of irrigated agriculture and large tracts of pasture and dry cropland. The region has a diversified agricultural economy based on ranching, dryland farming, irrigated specialty crops and intensive feedlot operations, and it has a significant oil and gas industry. The population of the sub-basin is primarily rural, broadly scattered in farms and small towns and hamlets such as Manyberries in the east and Warner, Raymond and Stirling in the west.
Regionally Significant Areas
During high water years, Pakowki Lake is a very productive waterfowl area. The lake is a major stop on a North American waterfowl flyway and is considered internationally significant for its shorebird and waterfowl habitat. The International Union for Conservation of Nature (IUCN) has classified Pakowki Lake as a Category IV Habitat/Species Management Area, and Pakowki Lake is also listed by Bird Studies Canada and Bird Life International as globally significant for congregatory species and waterfowl concentrations, and nationally significant for congregatory species and shorebird concentrations. The area was also designated an Important Bird Area (IBA) in the early 2000s to identify it as a globally important conservation priority. A site is recognized as an IBA only if it meets certain criteria, based on the occurrence of key bird species that are vulnerable to global extinction or whose populations are otherwise irreplaceable. Part of the lake is designated a Provincial Game Bird Sanctuary and hunting of game birds is prohibited except with a special permit.
According to the Pakowki IBA site listing, a 1998 colonial water-bird survey found the following species nesting on the lake: California Gull (730 nests), Double-crested Cormorant (136 nests), and Common Tern (185 nests). Other breeding species include Black-crowned Night-Heron, American White Pelican, Eared Grebe, Ring-billed and Franklin’s gulls, Black-necked Stilts, and White-faced Ibis (108 surveyed in 1996). The Piping Plover (nationally endangered) was found in 1998, with only one bird seen during the breeding season. Breeding land birds include the prairie population of Loggerhead Shrike, Sprague’s Pipit (both nationally threatened), Ferruginous Hawk and Sharp-tailed Grouse (both nationally vulnerable).
Southern Alberta is well known for its paleontologically significant Cretaceous sediments. In the late 1980s, Devil’s Coulee (previously named Fossil Coulee) became internationally famous as the site of a globally significant discovery of fossilized eggs and embryonic bones of duck-billed dinosaurs. The site proved to be very productive yielding eggs (many with embryos), dinosaur hatchlings, at least nine separate nests (one containing a clutch of eight eggs), and 20,000 isolated eggshell fragments. After the discovery, the town of Warner set up the Devil’s Coulee Dinosaur Heritage Museum as an interpretive centre.
Risks and Pressures
Alberta Wilderness Association (AWA) has classified a “Pakowki Lake Area of Concern” of approximately 380 square kilometres in this sub-basin, contiguous with two other AWA Areas of Concern: Milk River–Sage Creek and Cypress Hills. AWA considers this area to be of national environmental significance and they include the intermittent lake itself, as well as the surrounding prairie uplands and a large sand dune–wetland complex which includes extensive bulrush marshes. AWA concerns centre on the fact that Pakowki Lake is an important staging area for migrating shorebirds and provides a nesting area for birds that occur in few other places in Canada. The AWA also states that the area is important for rare and uncommon plants found in the sand dune and wetland habitats. Significant, rare or uncommon plants within this sub-basin include Western Spiderwort (nationally threatened), Smooth Goosefoot (nationally vulnerable), Great Basin Downingia (nationally rare), Sand Nut-grass, and Annual Skeletonweed.
Interesting fauna found at the site include Pronghorn Antelope – especially in key habitat areas along the east shore – and the rare Plains Hognose Snake. Most other animal species found in this sub-basin are common throughout the entire watershed.
One of the major threats to the waterfowl using Pakowki Lake is outbreaks of avian botulism, a naturally occurring food poisoning that affects many bird species – primarily waterfowl and shorebirds – throughout the world. Although any water body used by waterfowl is a potential site for botulism, some lakes have a history of recurrent problems and Pakowki Lake has suffered extensive waterfowl losses in the past. The disease struck from 1994 to 1997, and according to Bird Studies Canada, in 1995 alone 100,825 dead birds were collected including Green-winged Teals, Northern Pintails, Northern Shovelers and Mallards.
Drought and climate change:
The entire region is historically subject to drought, and rivers within the SSRB are considered to be some of the most climate change sensitive and vulnerable watersheds in Canada. Because Pakowki Lake is fed by intermittent streams it is particularly susceptible to drought conditions and its productivity has declined in recent years due to prolonged drought.
Landscape pressures in this sub-basin mirror those of other sub-basins and are primarily related to agricultural development (drained wetlands, cultivation of native grasslands, altered shorelines); and oil and gas exploration and development. Livestock activity, recreation and pipeline crossings have affected the integrity of river and stream banks within the sub-basin, and oil and gas activity is high throughout the region. Oil and gas development impact the landscape through road construction, alteration of native habitat and introduction of invasive species. Seismic testing has indicated the presence of Nisku oil in the Pakowki Lake – Manyberries area and recommendations have been made for “more detailed” seismic evaluation.