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The spatial distribution of source areas and associated residence times of water in the catchment are signi®cant factors controlling the annual cycles of dissolved organic carbon (DOC) concentration in Deer Creek (Summit County, Colorado). During spring snowmelt (April±August 1992), stream DOC concentrations increased with the rising limb of the hydrograph, peaked before maximum discharge, then declined rapidly as melting continued. We investigated catchment sources of DOC to stream¯ow, measuring DOC in tension lysimeters, groundwater wells, snow and streamow. Lysimeter data indicate that near-surface soil horizons are a primary contributor of DOC to stream¯ow during spring snowmelt. Concentrations of DOC in the lysimeters decrease rapidly during the melt period, supporting the hypothesis that hydrological¯ushing of catchment soils is the primary mechanism aecting the temporal variation of DOC in Deer Creek. Time constants of DOC¯ushing, characterizing the exponential decay of DOC concentration in the upper soil horizon, ranged from 10 to 30 days for the 10 lysimeter sites. Dierences in the rate of¯ushing are in¯uenced by topographical position, with near-stream riparian soils¯ushed more quickly than soils located further upslope. Variation in the amount of distribution of accumulated snow, and asynchronous melting of the snowpack across the landscape, staggered the onset of the spring¯ush throughout the catchment, prolonging the period of increased concentrations of DOC in the stream. Stream¯ow integrates the catchment-scale¯ushing responses, yielding a time constant associated with the recession of DOC in the stream channel (84 days) that is signi®cantly longer than the time constants observed for particular locations in the upper soil.