"Negatively buoyant jets, or sinking jets, can be observed in many problems of pollutant discharge. Any chemical waste that is heavier than the receiving water into which it is discharged may act as a negatively buoyant jet. In addition, when water is taken from the hypolimnion of a deep lake or reservoir and used as cooling water, the temperature, and consequently, the discharge may behave like a negatively buoyant jet. Two existing jet diffusion models have been utilized to predict the trajectory and dilution of a positively buoyant jet, or a rising jet, and have been modified to account for the sinking effect. Twenty-four experimental investigations were conducted involving different combinations of densimetric Froude number, velocity ratios, and initial angle of discharge. Salt was used as the tracer, yielding a fluid that was denser than the ambient receiving water and facilitated measuring concentration profiles of the jet plume. The coefficient of entrainment, the major mechanism of dilution, was determined as a function of the densimetric Froude number, velocity ratio, and initial angle of discharge. The reducted drag coefficient was chosen as zero for both models since any other value would predict a trajectory whose rise would be less than experimentally observed. For all angles of discharge the entrainment coefficient increased with a decrease in the velocity ratio and with an increase in densimetric Froude number. Additionally, there was a marked decrease in the entrainmnet coefficient with a decrease in the initial angle of discharge."--Page ii.