This report describes the instrumentation, methods, and preliminary results for a study of evapotranspiration in a grassland in Snively Basin of the Arid Lands Ecology Reserve in south-central Washington. Instrumentation was used to collect data at the site from May 30 to October 15,1990. Evapotranspiration was calculated by the Bowen-ratio and Penman-Monteith methods using collected data. Both methods are energy-balance approaches frequently used to estimate evapotranspiration for semiarid areas.