Measurements of CO2 near the snow-soil interface showed elevated concentrations up to 2120 ppmv. Concentrations greater than 1700 ppmv were observed 0.45 m above the snowsoil interface. The increase in CO2 concentrations in the snow coincided with the beginning of melt. Measurements of the pH and alkalinity of the meltwater from the base of the snowpack were consistent with the measured CO2 levels. Decreases in pH at constant alkalinity of up to 0.8 units were associated with the excess CO2. The origin of the excess CO2 is uncertain but may be related to litter decomposition. Elevated levels of CO2 near the snow-soil interface at the start of melt could have important effects on meltwater chemistry, especially since streams at this time flow under a covering of snow preventing equilibration with atmospheric CO2.