What’s in a Name?

ssask_basin3Large drainage basins are typically divided into smaller units, either “sub-basins” or “sub-watersheds,” to make them easier to manage.

The Government of Alberta defines the larger basin formed by the Bow, Oldman, Red Deer and the Alberta portion of the South Saskatchewan Rivers as the South Saskatchewan River Basin (SSRB). As part of the SSRB, the Alberta portion of the South Saskatchewan River is considered a sub-basin: a smaller, regional drainage area that contributes to the broader basin.

Those who live in the SEAWA watershed typically consider their corner of south-east Alberta (the area that drains towards the South Saskatchewan River) as the South Saskatchewan River Basin.

For the purpose of the State of the Watershed report, and to reflect hydrologic, not political boundaries, SEAWA refers to the Alberta and Saskatchewan portions of the basin as the SEAWA watershed, or the South Saskatchewan River Sub-basin (SSRSB). The SEAWA watershed has been further divided into six sub-watersheds based on the unique drainage patterns and characteristics of the regional landscape.

Divider Description and Topography – South Saskatchewan River Sub-basin (SSRSB)
click on map for a larger view
mapbasinThe SEAWA watershed, also known as the South Saskatchewan River Sub-basin (SSRSB), is located in the south east region of Alberta, roughly centered around Medicine Hat area.

Agricultural land use accounts for 80% of the SSRSB’s total land. About 25% of agricultural land is used for crops, while the majority, 63%, is used for pasture. Thousands of oil and gas wells are operated within the region, with the majority of gas processing plants located near Empress.

CFB Suffield, covering some 2,700 square kilometers offers one of the largest live-fire training areas in North America for military use. The Base has set aside 458 square kilometers for a National Wildlife Area, meant to preserve the local wildlife and fragile ecosystem.

The Cypress Hills rise 600 meters above the surrounding land and cover about 2,600 square kilometers, stretching across the Alberta-Saskatchewan border. Their highest point, Head of the Mountain, is 1,466 meters above sea level. It is the highest point of land between the Rocky Mountains and Labrador. The western part of the Cypress Hills lies within the SSRSB.

In Saskatchewan, the basin covers parts of the rural municipalities of Maple Creek, Big Stick, Piapot, Gull Lake, Enterprise, Fox Valley, Pittville, Deer Forks, Happyland, Clinworth, Chesterfield, Newcombe, Milton, Kindersley, Antelope Park, Prairiedale and Heart’s Hill. The area extends west to Milk River Ridge, south to Pakowki Lake, east to the rural municipality of Pittville, and north to the rural municipality of Heart’s Hill.

The southern boundary of the SSRSB lies on the boundary of two major river basins. The basin to the south is the Milk River Basin, which is part of the Mississippi-Missouri River system.


Read more… about the South Saskatchewan River Sub-basin (SSRSB)
Read more… about the geography of the South Saskatchewan River Basin (SSRB)
Read more… about the North and South Saskatchewan River Basins


The population of the SSRSB is estimated at approximately 66,000 people residing in an area of 14,000 square kilometres, which translates into 4.7 people per square kilometre.


There are five Districts included in the SEAWA Basin (either entirely or partially), Cardston County, County of Warner, County of Forty Mile, County of Lethbridge, Municipal District of Taber, Cypress County, County of Newell, Special Area No. 2, Special Area No. 3, and the Municipal District of Acadia. Major population centers include the City of Medicine Hat, the towns of Redcliff and Bow Island, the Village of Foremost, and CFB Suffield.

The population is predominantly urban, and the urban population is growing at a faster rate than the rural population. The largest urban center is Medicine Hat, which had a population of 60,426 in 2008.

Read more… about the demographics and profiles of communities in the South Saskatchewan River Sub-basin (SSRSB).

Read more… about the demographics and profiles of rural communities in western Canada.

Rivers and Reservoirs

Some of the major bodies of water in the SSRSB include Pakowki Lake, Milk River Ridge Reservoir and Many Islands Lake. Pakowki Lake is located about 100 km south of Medicine Hat and 30 km north of the U.S. border. It is an intermittent lake, and it has undergone cycles in water level which have lasted several years. In a 1996 study, its area was about 109 km2. Its only inflow stream is Etzikom Coulee, a long glacial spillway channel. Marsh habitat and sand dunes are located near the lake.
ssask1Several other notable bodies of water are in the vicinity of the SSRSB. Chappice Lake is a small saline lake located about 20 km northeast of Medicine Hat. It is less than one meter in depth. The lake used to be fed by a stream from the northeast, but in 1978 a weir was constructed in this location, preventing surface water from flowing in.

Elkwater Lake is located in Cypress Hills Provincial Park. Its outlet has been artificially deepened to increase water flow to the nearby reservoir.

Travers Reservoir is a man-made reservoir built on the Little Bow River, about 35 kilometers southeast of the town of Vulcan, with an area of 22.5 square kilometers. It was constructed in 1954 to store water from the Bow River. White Horse Lake, Dishpan Lake and Easy Lake are located in Canadian Forces Base Suffield, in the Middle Sand Hills area.

The St. Mary River Irrigation District is a large system of canals and pipelines covering over 150,000 hectares. A large part of this is in the SEAWA management area. The entire irrigation area is south of the Oldman and South Saskatchewan rivers, extending from Medicine Hat in the east to Lethbridge in the west.

Read more… about major bodies of water in the South Saskatchewan River Basin (SSRB).

Riparian, Wetland, and Protected Areas

The prairies of Alberta contain numerous wetland areas. Wetlands are places where the land has been saturated with water long enough to have poorly drained soils. Unlike lakes, some wetlands do not have well-defined boundaries, and some are not permanent. Most wetlands in southern Alberta are temporary, with water accumulating in the spring. Over 60% of the wetlands in southern Alberta have been drained.


The main types of wetlands located in central and southern Alberta are marshes and ponds. These types of wetlands differ by their structure and the wildlife which live there. Marshes (sloughs) form as water drains into depressions to create pools of still water which contain high levels of nutrients. Ponds are still-water basins which are wide and generally shallow. Water in ponds is accumulated from precipitation or groundwater sources. Ponds can undergo dry periods in the late summer.

Prairie marshes, also known as prairie potholes or sloughs, are depressions of about 30 to 80 meters in diameter which formed during recent ice ages. These potholes were later partially filled with sediments.

The SSRSB is part of the Prairie Pothole Region, a large area that covers much of southern and eastern Alberta, southern Saskatchewan, North Dakota and South Dakota. Many of these depressions resulted from melting glaciers. Prairie wetlands often act as groundwater recharge or discharge sites. Because the prairies experience wet and dry periods, some of the wetlands can dry up for several years. When this happens, different types of plants may begin to grow. Most depressional wetlands do not have inflows or outflows on the surface. Depressional wetlands that provide groundwater recharge tend to have lower salt content, and those that receive groundwater discharge tend to have higher salt content.

Read more… about protected areas and regions in the South Saskatchewan River Sub-basin (SSRSB).

Master Agreement on Apportionment

The Master Agreement on Apportionment states that all eastward flowing streams are subject to apportionment. The Prairie Provinces Water Board (PPWB) administers the Master Agreement on Apportionment, signed on October 30, 1969 by Canada and the provinces of Alberta, Saskatchewan, and Manitoba.

The Agreement provides for an equitable sharing of available waters for all eastward flowing streams that cross interprovincial boundaries, including interprovincial lakes. It also serves to protect interprovincial aquifers and surface water quality. Schedules to the Agreement describe the role of the Board, stipulate how the water shall be apportioned, and set water quality objectives for the water passing from Alberta to Saskatchewan and from Saskatchewan to Manitoba.

Read more… about Master Agreement on Apportionment.


Ecozone. Ecosystem. Ecosphere. Ecoregions. What’s the difference between all these “ecowords”? It’s all relative, starting with anecosystem, which is a natural community that can exist anywhere on earth. Combining the word eco, which means habitat, and system, which refers to the interdependent way natural elements fit together, an ecosystem can be as big as the planet or as small as the palm of your hand. An ecozone is a relatively large ecosystem. And the ecosphere is the largest of them all.

An Ecoregion is an area of similar climate, physiography, vegetation, soil, water, fauna and land use characteristics. Climate strongly influences many of the other characteristics in an ecoregion, such as soils, vegetation, water, fauna and land use.

Read more… about the ecoregions and ecozones across the entire South Saskatchewan River Basin.