A literature review and laboratory study were made of the effects of water temperature and turbulence on dissolved oxygen and BOD in streams. Methods used to calculate the effects of pollution upon the assimilative capacity of a stream are reviewed. The equations available in the literature make possible calculations of BOD and dissolved oxygen concentrations if initial conditions and dynamic parameters are known. A series of simulated DO sag curves under varying conditions of temperature and turbulence were developed in the laboratory. These were accomplished by probe measurements of dissolved oxygen in a series of test solutions to which glucose feed solutions were added. The stream parameters were estimated and the parameter delta, the incremental DO change, was calculated under each test condition. A plot of temperature versus delta and turbulence versus delta demonstrated that the parameter was of a physical nature. This concept of delta allows an investigator to predict a range of dissolved oxygen values given a set of initial conditions. The probability of any actual DO value falling within this range may also be obtained, allowing intelligent pollution control decisions to be made based on the probability function. (Knapp-USGS)