In Crestmont many backyards have concrete swales that run along the rear property line. The purpose of the swale is to convey water overland (via the swale) to the nearest catch basin. The City of Calgary has instituted a lot drainage bylaw which helps homeowners to understand what their obligations are when it comes to appropriate water use and drainage for Calgary’s storm water system.
It is a requirement to keep surface drainage facilities on private property (known as "Overland Drainage Right-of-Way" (ODRW) including swales and catch basins/drains) clear of any soil, silt, yard waste or any other matter that may obstruct, restrict or prevent the flow of water. Buildings or structures cannot be constructed or placed on or over the surface drainage facility. If a fence must be built over the facility, there must be at least 6 inches (15 cm) of clearance between the facility and the bottom of the fence.