The term spiraling has been used to describe the combined processes of cycling and longitudinal transport in streams. As a measure of organic C spiraling, organic C turnover length, S is introduced, defined as the average or expected downstream distance traveled by a C atom between its entry or fixation in the stream and its oxidation. Using a simple model for organic C dynamics in a stream, it is shown that S is closely related to Fisher and Likens'' ecosystem efficiency. Unlike efficiency, S is independent of the length of the study reach, and values of S determined in streams of differing lengths can be compared. Using data from 3 differnet streams, the relationship between S and efficiency to agree closely with the model prediction was found. Hypotheses of stream functioning are discussed in the context of organic C spiraling theory.