To understand the carbon and energy exchange between the lake surface and the atmosphere, direct measurements of latent, sensible heat and CO2 fluxes were taken using the eddy covariance (EC) technique in western Lake Erie during October 2011-September 2013. We found that the latent heat flux (LE) had a marked one-peak seasonal change in both years that differed from the diurnal course and lacked a sinusoidal dynamic common in terrestrial ecosystems. Daily mean LE was 4.8±0.1 and 4.3±0.2 MJ m-2 d-1 in Year 1 and Year 2, respectively. The sensible heat flux (H) remained much lower than the LE, with a daily mean of 0.9±0.1 and 1.1±0.1 MJ m-2 d-1 in Year 1 and Year 2, respectively. As a result, the Bowen ratio was