It was decided to construct 40,000 m3/day desalination plant in Hurghada City, the Arab Contractors Company was assigned to construct the intake and the outlet for the desalination plant, the company already constructed the outlet pipe lines with three poly ethylene pipe lines with diameter 630 mm each. A decision was made to increase the plant capacity to be 80,000 m3/day, due to that a modifications have to be made to the original design of the intake and the outlet pipe lines, Hydraulics Research Institute HRI was commissioned by the Arab Contractors to conduct the hydraulic studies for the intake and extension of the outlet. The aim of the study is to modify the hydraulic design of the pipeline intake, in addition to investigate the recirculation of the effluents brine discharge which may reach the intake of the plant, the salinity distribution in the plant vicinity and the plume transport and dispersion in the plant vicinity. To achieve the aim of the study a hydrodynamic and dispersion numerical model study was carried out. A three dimension hydraulic numerical model with five layers along the water column was carried out to account for the stratification which may occur in front of the plant due to the density difference induced by the salinity variation. Twelve model scenarios were setup to account for three different outfall alternatives tested. The results of the model simulations show the followings: • The locations of the outfall pipelines in alternatives 1 and 2have a recirculation of the effluent discharge from the outfall of the plant to its intake. • The proposed location of the outfall pipelines in alternative-3 gives better results compared with the results of alternatives 1 and 2 from the recirculation point of view. • Outfall diffuser cause more dilution of the effluent discharge and better mixing of the effluents with the see water. Therefore, it gives better results compared with the normal onshore outfall structure. • The wind condition almost has very small effect in transporting the brine discharge, since the brine plumes concentrated near to bottom of the sea.