The theory of waste assimilation in flowing streams has long been understood and, in a few cases, the application of theory has been made. A basic need in this field lies in the understanding of the behavior of the various components of reaeration and how these differ according to stream type and prevailing climatological conditions. A method is presented which can be used to separate and measure the components of reaeration in flowing waters. Plastic chambers are used to separate the effects of photosynthesis, diffusion, and respiration on the oxygen balance of a stream's regimen and further separate these parameters according to the benthos and organisms which are free-floating. Dissolved oxygen measurements were made in conjunction with supporting information such as atmospheric pressure, temperature, stream velocity profile, light intensity, and the percent of light transmittance to the benthos.