Evapotranspiration is a fundamental component of the hydrologic cycle. According to Environment Canada, on average, as much as 40% of precipitation in Canada is evaporated or transpired. Since evaporation makes up a considerable portion of the water budget, its variability will therefore have proportionally larger impacts on all other related processes. For example, evaporation impacts flood prediction, irrigation, crop growth, hydroelectric production, water navigation, diseases, indigenous peoples’ health and food supply and the carbon budget (Bonan, 2002). A literature and database evaluation on evapotranspiration within the Ontario, Canada region will better inform the Toronto and Region Conservation Authority (TRCA) on their future endeavours to study evaporative fluxes, a critical component of the water budget of watersheds like the Humber River watershed. Future TRCA projects that incorporate the collection of hourly data on evaporative fluxes can provide a better understanding of the hydrology of watersheds including factors generating floods. The measurement regime in identifying the causes for the variability in evaporative losses can thereby strengthen land‐use planning and management decisions. The missing gaps in existing data will identify the potential for enhanced measurement programs in the province.