When heated water from a thermal power plant is discharged onto the free surface of an estuary or river, a density stratified flow consisting of superposed layers of hot and cold water is established. Such a flow is characterized by an initially stable interface at which there is zero velocity difference and a decaying density difference. Since it is known that after the density difference has decayed sufficiently the interface will be destroyed by turbulent eddies generated at the bottom boundary, it is pertinent to inquire if the point of interfacial stability can be easily located. It is the purpose of this paper to examine the question of interfacial stability in the presence of boundary generated turbulence and in the absence of interfacial shear. Although the problem of interfacial stability has been previously investigated, scant attention has been given to the case of a two layer flow without shear in the presence of boundary generated turbulence. Keulegan (1949) investigated a turbulent current of fresh water moving over a quiescent pool of saline water. He concluded that the stability of the interface could be adequately described by a single dimensionless parameter, the "Keulegan" number.