The storage and cycling of water across landscape units plays a critical role in ecosystem function. In recognition of their vital ecohydrological role, lakes have been integrated into the broader reclamation strategy in the Athabasca Oilsands Region (AOSR). While pilot-scale pit lakes have been constructed, identifying, and understanding the key parameters and how they upscale to larger, commercial-scale systems is critical. Determining these key factors and potential design limitations is required to adequately create functioning pit lake ecosystems. Here, we examine the evaporation dynamics and energy budget of natural, undisturbed lakes in the AOSR, in the context of their application to advance reclamation efforts, through evaluating key drivers such as lake morphometry, the influence of surrounding land units and climate. Results depict the influence of lake morphometry on heat storage and ET fluxes, with larger lakes exhibiting greater evaporation compared to smaller systems, as well as temporal trends where larger lakes warmed slower but retained heat later into the season resulting in continued evaporation into the fall. Adjacent land units influenced the composition of the water column profile, where lakes flanked by forests received less organic matter inputs than those flanked by fens, resulting in a clearer water column explaining some of the variability in energy partitioning. Assessment of evaporation rates across a combination of various-size lakes provides important insight into considerations for system design. Moreover, data from reference lakes provides context to the data collected at constructed sites which helps establish metrics of ecosystem function, trajectory, and success.