Remotely sensed data acquired using the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) at two irrigated hybrid poplar plantation sites located in Oregon and Washington States were used to assess the feasibility of using AVIRIS retrieved column water vapor as a measure of evapotranspiration (ET) of poplar plantations. AVIRIS data collected on four different days in the summers of 1996, 1997 and 1998 were used to derive column water vapor over the sites. To relate column water vapor to poplar ET, we developed a hypothesis, which was used to infer the relationship between the two variables. The approach tested consisted of delineating homogenous vegetated patches and averaging the column water vapor to determine the downwind spatial distribution pattern (trend) in the water vapor signal. The results indicate that the poplars were transpiring at rates characteristic of vegetation under unlimited soil moisture conditions and that the vertical distribution of water vapor was chiefly driven by forced convection. The concentration and the observed trends in the column of water vapor over the vegetated patches were related to the moisture condition of the land cover upwind of their location, and the trends were best described by linear or quadratic functions. To give an idea of the strength of moisture flux in the AVIRIS vapor signal, latent heat fluxes were estimated, based on the slope of the trends. Comparison of the AVIRIS values with flux estimates at the Boardman site lend credence to the potential for AVIRIS retrieved column water vapor in fields such as ecology, agriculture and meteorology.