Weed Control on Highways in the Calgary Area

The negative impacts of invasive species cost the Alberta economy thousands of dollars annually and can result in even greater ecological losses. These may come in the form of habitat loss, displacement of native plants and decreased land productivity, in addition to direct financial costs of preventing and controlling infestations. The Alberta Weed Control Act regulates the control of invasive species in Alberta, and recognizes three classes of weeds; restricted, noxious and nuisance. Enforcement of the Act is the responsibility of local municipalities. The regulatory environment is complicated by the fact that individual municipalities have the power to upgrade the status of a weed to a higher class within the municipality, resulting in unique requirements in certain areas of the province. A number of Best Management Practices (BMPs) are currently in place to address invasive species management issues during highway construction. These include pre-disturbance weed surveys, use of native seed, cleaning of construction equipment and soil handling best practices, among others. Despite best efforts, the disturbance created during construction often provides an opportunity for invasive species to establish (or expand) a foothold. Once established, infestations can be quite difficult to control, even under ideal conditions. Proximity to sensitive areas, landowner limitations, and site stability concerns can further limit control options. Addressing the infestation often requires a multifaceted approach. In this presentation, examples of context-appropriate BMPs implemented on recent road projects in the Calgary area are described, including follow-up treatments and lessons learned.