Cochrane’s draft wetland conservation policy is before the public for comment over the summer. This policy will provide Council’s directives to administration about how they intend to “direct, control, and manage” local wetlands. As currently drafted, the proposed policy perpetrates the myth that wetlands might exist and function in isolation from the geology, hydrology, vegetation, biodiversity and adjacent riparian lands required to sustain them. At a minimum, the policy ought to reflect four fundamental wetland relationships:
the interconnections and interdependencies of wetlands as geopolitical-land-locations where water is present at different times of the year, affecting the ability of humans and other species to utilize these lands for a variety of purposes;
the interdependence of all wetlands within a wetland complex;
the relationship between and among a wetland, its wet meadow area that fluctuates in extent and functionality on a seasonal and ongoing basis, and its associated riparian lands; and
the relationship between and among wetlands and other surface water bodies and aquifers, springs and seeps in the watershed within which they are located.
In 1998, in her book Fresh Water, natural scientist E.C. Pielou estimated that 15% of Canada’s total land mass is composed of wetlands. She explained that a little over 10,000 years ago the last ice sheets receded from southern Alberta, Saskatchewan and the northern mid-western states leaving behind 4-5 million prairie potholes in the “knob and kettle” landscape carved out by the melting and receding ice. Most of Cochrane’s wetlands were formed this way as immature or incomplete drainage systems in poorly drained rolling terrain. Pielou explained that the melting glaciers did not leave behind a consistent enough flow of water to erode the soils to form a linked natural drainage course that would eventually form a stream or creek. In Cochrane, these small wetlands (most are less than 50 m across), with their tell-tale associated riparian vegetation, are commonly referred to as sloughs, but are also known as swamps and marshes. Peilou explained that while both swamps and marshes have some open water during the spring and summer months, swamps tend to retain open water most of the year and are surrounded with trees and shrubs, while marshes may have visible open water for part of the year with distinctive plants, like sedges, cattails and reeds growing in their wet meadow areas year round. No matter what you call them, Cochrane’s southern and northern plateaus are dotted with numerous prairie pothole wetlands: 204 wetlands reportedly remain, but since the inventory was created in 2012, there have been at least two subdivision applications made with corresponding applications to Alberta Environment and Sustainable Resource Development (AESRD) to enable the developer to remove all the seasonal (Class 1, 2 and 3) wetlands from the land area subject to subdivision. Where wetland complexes once flourished in relation to one another, the area now boasts a residential community with perhaps one wetland remaining.
Until recently, when Cochrane annexed lands on the southern and northern plateaus of the Bow River valley, the area’s wetland inventory remained relatively stable, albeit the wetlands were degraded through agricultural operations. However, degraded wetlands are not insignificant, and in many cases, can be restored to their full natural functions. As Cochrane continues to urbanize the southern and northern plateaus, all the wetlands in the illustration provided with this article are under siege.
Cochrane’s wetlands exist in wetland complexes of two or more prairie potholes that are somehow interconnected in their seasonal and year round functionality. Society doesn’t fully understand the interconnectedness, and cannot predict with certainty how the wetlands are related to one
another or how the different functions of different classes of wetlands in a complex are necessary for normal wetland functions. But, where all classes of wetland, except the permanent ponds with water visible 7-12 months of the year, are removed during subdivision and development, the permanent wetlands change. In some cases, they flood well beyond their original beds and shores and wet meadow areas. In other cases, they lose their natural vegetation and become heavily inundated with algae. These changes are visible to the eye, but there are multiple changes happening below the surface: these include changes to plant growth, oxygen levels, and adaptive processes to deal with increased sedimentation which adds nutrients and affects absorption of sunlight. Loss of indigenous species and introduction of invasive species is common. Given sufficient time, most wetlands will recover but not necessarily to their original state. They may flip to a completely altered but stable state: those changes may not be what humans expect or want from their urban wetlands.
The proposed wetland policy simply codifies existing Town practices based on the mythology that one wetland may be conserved and managed on the landscape without its associated natural infrastructure. Where wetland complexes of anywhere from 5-45 wetlands were once situated, Cochrane now might have 5-200 new buildings surrounding one wetland with a 6 metre riparian “buffer” around its perimeter. Where one or two wetlands are retained as isolated “ponds”, they are used for storm drainage collection, or treatment, or both, with associated algae growth during the summer months. Natural linkages and interdependencies are replaced with buildings, roads, and pavement that increase both the volume and rate of flow of snow melt and storm drainage, swelling the ponds to unnatural levels and killing the trees and willows.
To change the way wetlands are conserved and managed, Council needs to understand the shared community values about wetlands. Do you want to continue to perpetuate the mythology that it is ok to destroy all seasonal prairie potholes on the landscape and retain only the permanent ponds? Can you be sure that our ecology, societal values, and economy will not be affected if this practice continues? How will the landscape sustain wetland functions, such as seasonal water retention for release during drought conditions, and flood control? When almost all the wetlands are gone, will landowners have the same peaceful and quiet enjoyment of their urban properties?
Next week, the article will address the mythology that environmental reserves are a panacea for wetland and riparian land conservation and management. If you have any questions about anything you read in this series on wetlands, you can contact me at email@example.com.