Salinity tolerance is an important adaptive trait for land reclamation, particularly after petroleum extraction from the Athabasca oil sands “gigaproject” in western Canada. We compared survival, biomass yield and allocation, and biochemical efficiency for three willow species: Salix discolor (DIS), S. eriocephala (ERI), and S. interior (INT) grown under control (CTL) and medium and high salinity treatments (MST and HST). In HST, all DIS and ERI plants died, but 33% of INT plants survived. For DIS and ERI, total aboveground (AG) dry mass decreased from CTL to MST, whereas for INT, AG dry mass increased slightly in MST and also increased further in HST. Stem length was not influenced by salinity treatment; however, there was a significant treatment x species interaction for basal diameter resulting from a basal diameter decrease in DIS and ERI and increase in INT with increasing salinity. Underlying traits related to photosynthesis showed equal or greater values for DIS and ERI in MST compared with CTL, but INT displayed a greater stimulation (1.3x) in the MST and HST. The saline tolerance of INT may be due to natural selection in the arid regions of the southwest USA, where it is thought to have its evolutionary origins.