History and Overview
The Seven Persons Creek sub-watershed is located primarily south and west of Medicine Hat and includes parts of the City of Medicine Hat, Cypress County and the County of Forty Mile. The sub-watershed also includes a small piece of the County of Warner and a small portion of the M.D. of Taber along the western edge of a narrow band that stretches towards Lethbridge.
The topography of slightly-rolling grassy hills and deep coulees is similar to other regional watersheds; land that was glacially scoured and subsequently shaped by huge volumes of meltwater which occasionally cut through the glacial debris to form long and narrow, now typically dry, flat-floored valleys. In this corner of the province several of these long glacial spillways – including Forty Mile, Verdigris, Chin and Etzikom Coulees have been dammed to form off stream storage reservoirs. There are a number of other water bodies within the watershed including Cavan Lake Municipal Recreation Area, Elkwater Lake at the base of Cypress Hills, and Bullshead Reservoir west of Elkwater.
The sub-watershed includes the north-western slopes of the Cypress Hills, a dramatic feature of the southern prairies widely noted as the highest point in Canada between the Rocky Mountains and Labrador. The West (Alberta) Block of the Cypress Hills acts as a “continental divide.” While streams on the northern slopes flow towards the South Saskatchewan River, Battle Creek flows east from its source in the Alberta portion of the hills, then south-eastward in Saskatchewan, feeding eventually into the Mississippi River system in the United States.
The ecology of this sub-watershed is predominantly grasslands because it is located in the Dry Mixedgrass natural sub-region of Alberta. The highlands of the Cypress Hills however are a bio-diverse mix of highly productive forests, wetlands and grasslands, and according to Alberta Environment the combination of plant and animal species living there is unlike any other in Canada.
Forty-seven mammal species, including moose, elk (Wapiti), white-tail and mule deer, pronghorn, red fox, porcupine and bobcat also live within the Cypress Hills, as well as three important amphibian species – boreal chorus frog, tiger salamander and Alberta’s largest and most threatened frog, the Northern Leopard Frog. More than 700 species of plants thrive in the Hills including 18 species of orchids.
Other environmentally significant habitats have been recognized in this region for several plants, birds and wildlife including most frequently Ferruginous Hawks and Burrowing Owls, and also for the Northern Leopard Frog, Great Plains Toad and Short-horned Lizard, Alberta’s only native lizard species. Red Rock Coulee Natural Area, south of Medicine Hat, is designated as a natural area mainly because of its geological significance.
Risks and Pressures
Landscape pressures mirror those of other sub-watersheds and are primarily related to agricultural development and oil and gas development. Oil and gas activity impacts the landscape through road construction alteration of native habitat, introduction of invasive species and creek crossings. Livestock activity and recreation have also affected the integrity of stream banks.