An analysis was made of water losses due to evaporation within the wetted area of a low application rate sprinkler system operating during daylight hours under conditions of slight to moderate breezes. The magnitude of evaporation loss from the sprinkled area was determined by measuring the absolute humidity, temperature, and wind speed profiles immediately upwind and downwind from a large bromus grass field where near-horizontal homogeneity existed prior to operation of the sprinkler. Sprinkler discharge rate and operating pressure had minimal effect on water loss. The losses were mainly evaporation from plant surfaces, and were as high as one-half of the sprinkler water discharge. The greatest decrease in evapotranspiration was adjacent to the wetted area. A field 70 meters downwind from the sprinkler line was unaffected. Approximately one-eighth of the water that evaporated within the sprinkled area was offset by a decrease in evapotranspiration in the first 70 meters downwind. (WRSIC abstract)