Evaporation from wetlands, lakes, and reservoirs represents an important, yet poorly quantified, hydrological flux. A wide range of estimation approaches are commonly used in practice (e.g. Penman, Priestley-Taylor, complementary-relationship methods, etc.) which can predict markedly different annual amounts. An improved understanding of the governing energy and mass transfer processes is needed to develop robust approaches to calculate open water evaporation rates, and to predict how climate change will impact them. This research reports eddy covariance measurements of evaporation above 2 contrasting open water surfaces: (1) a medium size reservoir and (2) a shallow saline wetland, both located in Saskatchewan. It is demonstrated that, in both cases, evaporation rates can be estimated with a high degree of accuracy using aerodynamic bulk transfer methods, where the evaporation fluxes scale with the turbulent friction velocity of the wind and the vapour pressure gradient between the water surface and atmosphere. The crux of the estimation problem is therefore to obtain accurate over-lake wind speeds, and their associated momentum fluxes, as well as the lake surface temperature. In this research we further examine the processes governing the momentum transfer (waves, wind speed-up, etc.) and similarly those governing the water surface temperature (energy storage, turnover, mixing, stability, etc.) and recommend improvements to current estimation approaches.