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Diel oscillations in discharge are common on most streams for most of the year. In winter, the diel or diurnal variability can result from daytime melting of snow and water conveyance in soil and streams (Caine, 1992). Later, in spring through fall, diel variability can occur from direct evaporation and solar radiation in daytime causing evapotranspiration to redirect groundwater towards the soil surface until night when water in the vadose zone resumes travel downslope (Burt, 1979). Evapotranspiration can also draw directly from groundwater reservoirs in daytime for replenishment by hyporheic exchange with the stream bed and banks at night.