Hot and cold springs contribute dead (14C free) dissolved inorganic carbon (DIC) to the Owens River and Hot Creek. Headwaters aquatic plants have modern 14C, but live plants downstream of the intracaldera springs are depleted in 14C, (as low as 19% modern, with apparent ages up to 13.3 kyrs). In an abandoned meander of the upper Owens River, preserved streambed plants are buried by 600 year old Inyo Craters pumice. Apparent 14C ages of these plants exceed true ages by ~1100 years indicating that they also incorporated dead DIC as they grew. The preserved plants are downstream of Big Springs, whose elevated dead DIC may represent magmatic CO2. The buried plants incorporated ~10% dead carbon, although modern plants here have ~50% dead carbon, suggesting that more magmatic CO2 is now entering the upper Owens River than at the time of the Inyo Craters eruptions 600 years ago. ¿ 1998 American Geophysical Union