This study's aim is using Delft3d software to simulate a chlorine containing water source to study the residual chlorine in a water stream. Cooling water of power plants is disinfected by chlorine. Although chlorine concentration is relatively low, its effect is major at low flow conditions. Effluent chlorine is subjected to different operations, dispersion, decomposition and ultraviolet decay. It also works as an oxidant on nitrogen containing organics such as ammonia to form chloramines components. In order to research the forms of chlorine, a 2d numerical model is used to simulate theses various operations. A hydrographic survey is performed to measure the bed levels. Water quality parameters are measured through in-situ and in lab measurements. Dairout thermal power plant in Beheira governorate at Rosetta branch is chosen to be studied due to its low flow conditions. Delft3d software is used to create a 2d hydro-dynamic simulation of the study area. FLOW module is coupled to water quality module DELWAQ. Finally, chlorinated water effluent was analyzed according to the concentration threshold in the standards and regulations.