Sea ice melt (SIM), meteoric water (river runoff net precipitation), and Pacific seawater contributions to the upper waters of the Canadian Arctic Archipelago (CAA), Nares Strait, and Baffin Bay during late summer 1997 and 2003 are estimated from salinity, δ18O, and nutrient data. Salinity-δ18O relationships within the study area suggest that the CAA inherits a net sea-ice formation (brine) signal from the Arctic Ocean. Inherited brine complicates the estimation of local contributions from sea ice melt and glacial runoff, especially where a significant component of the surface water derives from Arctic outflow. Our data are characterized by two linear relationships between salinity and δ18O, reflecting: (1) the mixing of deeper Atlantic seawater with brine-enriched halocline water of shelf origin and (2) mixing of halocline water with shallower waters freshened by meteoric water and local SIM. Inventories of Pacific water, meteoric water, net SIM, and local SIM were computed over the upper 150 m of the water column. Positive local SIM fractions were ubiquitous during late summer, with the largest inventories (>1 m) found on the eastern sides of Baffin Bay, Kennedy Channel, and Davis Strait. In the CAA and Baffin Bay, freshwater inventories were dominated by contributions from meteoric and Pacific water, with little input from local SIM. In Smith Sound, where comparable data were collected in 1997 and 2003, meteoric water inventories of 8–10 m were similar for both years, whereas the Pacific water inventory was substantially lower in 2003 (<80 m) than in 1997 (>100 m), implying that the export of meteoric water from the Arctic Ocean is decoupled from Pacific water outflow.