Most of the large surface reservoirs are stably stratified throughout most or all of the year. One means of assisting in the management is to allow for the selective withdrawal from the reservoir. The value of the intake's submergence when the upper layer fluids begin to be drawn into the intake is known as "critical submergence". In this study, the critical submergence for a circular intake pipe in a stratified body is investigated. Experiments were conducted on a vertically flowing downward intake pipe in a still-water reservoir. Experimental results are compared with that of the neuro-fuzzy models.