Preliminary investigations of constructed wetland ecosystems in the Athabasca Oil Sands Region have demonstrated meaningful functional similarities with regionally-abundant fens. Yet, incorporating constructed fens into the closure landscape will inevitably require these systems to be situated in configurations where key morphological characteristics are altered, will integrate materials with a greater diversity of hydraulic and geochemical properties, and must tolerate greater deviations from the design. It is currently unknown how these departures from the original design will impact water quality and quantity, which have a dominant role in fen ecohydrological function. Therefore, the goal of this study is to model the effects of altered morphology (length, width, slope, fen to upland ratio) and material hydraulic properties on water availability and peak sodium concentrations. Sensitivity analyses were conducted on fifteen morphological parameters in a three-dimensional groundwater flow and sodium transport model developed with MODFLOW-SURFACT. Preliminary results suggest that the slope of the upland, and position of high hydraulic conductivity features within the watershed have a pronounced influence on the hydrologic behaviour of the system. Anticipated results include the changes to average water table depth and peak sodium concentrations in the fen that occur with each design modification. Identifying the tolerance of constructed fens to design changes will provide reclamation practitioners and mine operators with a useful set of constraints to improve the chances of successful fen reclamation.