Stream temperatures as related to subsurface waterflows originating from irrigation.

Abstract

Continuous stream temperature data were collected from adjacent reaches of a third-order stream in eastern Oregon. The upstream reach was located within a non-irrigated meadow and the downstream reach was located within an irrigated meadow. Sensors were placed in the stream above a head-ditch irrigation diversion, in the irrigation ditch, in the subsurface (interflow) groundwater, and in the stream reach within the irrigated meadow. Daily maximum stream temperature in the reach located within the irrigated meadow was found to be 1 to 3 degrees C cooler than the non-irrigated reach. Daily minimum stream temperatures exhibited the opposite relationship with the reach within the irrigated meadow ranging from 0.5 to 1.7 degrees C warmer than the non-irrigated meadow reach.