Originally constructed in 1951, the Spray Canal hydroelectric facility is one of three TransAlta (TA) plants on the Spray system located immediately outside of Canmore, Alberta, Canada; which primarily generates electricity during periods of peak demand and supports overall system stability. The canal, approximately 4.7 km long with a crest elevation of approximately 1,684 metres above sea level (masl), has varying cross sections consisting mainly of earthfill embankments with a low permeability soil liner, combined with rock-cut sections. For most of the canal’s operating life, TA has closely monitored seepage progression surrounding the canal and has responded to the formation of sinkholes. Following an extensive review, with an options assessment completed in 2023, the decision was made to mitigate the seepage with a fit-for-purpose geomembrane. This paper will present the rehabilitation approach adopted at Spray Canal with a focus on the integration of design elements into the 2025 construction phase, preceded by an overview of the background leading up to construction, including rehabilitation options considered. The PVC geocomposite SIBELON® CNT 4600 was selected to meet the demanding environmental loads, the challenging geotechnical conditions, the limited two-month dewatering window, and the performance requirements of a coldclimate hydroelectric facility while providing a durable, long-term solution. The inherent adaptability of the selected system allowed for varied configurations with concrete ballast trenches and granular crest anchorage in fill areas, and stainless-steel anchorages on rock surfaces. Waterproofing works were completed during the summer and fall of 2025, totalling 600 m of lined canal.