The carbon isotope content of dissolved inorganic carbin (DIC) is measured for large, cold springs in the central Oregon Cascades. Low 14C activities in some of the springs are interpreted to result from the dissolution of diffuse magmatic CO2 emmisions. Volcanic activity, however, has not occurred in this area for more than 1300 years. On the basis of dissolved magmatic carbon concentrations in the springs, we infer a diffuse magmatic CO2 degassing rate of 170 tons/yr/km of arc for the central Oregon Casacdes. The mean intrusion rate of magmas beneath the arc inferred from the CO2 fluxes is similar to that estimated from heat flow studies.