We have studied weekly precipitation, snowpack, snowmelt, soil water and streamwater chemistry throughout winter for over a decade in a small (176 ha) northern Michigan watershed with high snowfall and vegetated by 60 to 80 year-old northern hardwoods. In this paper, we examine physical, chemical, and biological processes responsible for observed seasonal change in streamwater chemistry based upon intensive study during winter 1996±1997. The objective was to de®ne the contributions made to winter and spring streamwater chemical concentration and ¯ux by processes as snowmelt, over-winter forest ¯oor and surface soil mineralization, immobilization, and exchange, and subsurface ¯owpath. The forest ¯oor and soils were unfrozen beneath the snowpack which permitted most snowmelt to enter. Over-winter soil mineralization and other biological processes maintain shallow subsurface ion and dissolved organic carbon (DOC) reservoirs. Small, but steady, snowmelt throughout winter removed readily mobilized soil NO À 3 which resulted in high over-winter streamwater concentrations but little ¯ux. Winter soil water levels and ¯owpaths were generally deep which increased soil water and streamwater base cation (C B ), HCO À 3 , and Si concentrations. Spring snowmelt increased soil water levels and removal of ions and DOC from the biologically active forest ¯oor and shallow soils. The snowpack solute content was a minor component in determining streamwater ion concentration or ¯ux during and following peak snowmelt. Exchangeable ions, weakly adsorbed anions, and DOC in the forest ¯oor and surface soils dominated the chemical concentration and ¯ux in soil water and streamwater. Following peak snowmelt, soil microbial immobilization and rapidly increased plant uptake of limiting nutrients removed nearly all available nitrogen from soil water and streamwater. During the growing season high evapotranspiration increased subsurface ¯owpath depth which in turn removed weathering products, especially C B , HCO À 3 , and Si, from deeper soils. Soil water was a major component in the hydrologic and chemical budgets.