In this paper, two techniques to evaluate the dispersion of the effluent of an oil refinery are presented. Thus, the dispersion plume was characterized by field measurements of electrical conductivity and by computational simulation (Cormix simulator). An oil refinery whose effluent is discharged on the Atibaia river (Paulínia/SP) is taken as study case. The behavior of the effluent was evaluated until 1000 m after the discharge. The results show that the measurement of electrical conductivity is a suitable technique to evaluate the dispersion of oil refinery wastewaters, since they have high conductivity and for this reason there is a strong contrast between the values of the wastewater and the ambient background. Furthermore, other water quality parameters had a dispersion behavior similar to that shown by the conductivity. The dispersion plume generated by the computational simulator showed high concordance with the field data. In this manner, computational simulation can be a useful tool to evaluate the dispersion of discharges considering hypothetic scenarios, as well as to design the discharge channel.153251256Anuário Estatístico Brasileiro do Petróleo (2008) Gás Natural E Biocombustíveis, p. 2. , http://www.anp.gov.br/conheca/anuario_2008.asp, ANP (Agência Nacional do Petróleo), Seção, Acesso em: 27 mai. 2008(1998) Standard Methods For the Examination of Water and Wastewater, , APHA (American Public Health Association), 20. ed. Washington: APHA, AWWA, WPCFBaud, O., Toward nonintrusive flood discharge measurement (2005) Journal of Hydraulic Engineering, 131 (12), pp. 1031-1035Doneker, R.L., Jirka, G.H., CORMIX-GI systems for mixing zone analysis of brine wastewater disposal (2001) Desalination, 139 (3), pp. 263-274Doneker, R.L., Jirka, G.H., Hinton, S.W., A hydrodynamic mixing zone model and decision support system for pollutant discharges into surface waters (2007) Manual Do Usuário CormixJones, G.R., Buoyant surface discharges into water bodies. I: Flow classification and prediction methodology (2007) Journal of Hydraulic Engineering, 133 (9), pp. 1010-1020Machado, M.B., (2006) Modelagem Tridimensional Da Dispersão De Poluentes Em Rios, , Tese (Doutorado) - Faculdade de Engenharia Química da Universidade Estadual de Campinas, Campinas, SPMachado, M.B., Software para modelagem de dispersão de efluentes em rios (2008) Engenharia Sanitária E Ambiental, 13 (3), pp. 291-297Pun, K.-L., Field and model studies of water quality in Hong Kong (2006) The Environment In Asia Pacific Harbours, pp. 165-186. , In: WOLANSKI, E. (ed.), Netherlands: SpringerSantaella, S.T., Tratamento de efluentes de refinaria de petróleo em reatores com Aspergillus niger (2009) Engenharia Sanitaria E Ambiental, 14 (1), pp. 139-148Xia, L.P., Lam, K.M., Unsteady effluent dispersion in a round jet interacting with an oscillating cross-flow (2004) Journal of Hydraulic Engineering, 130 (7), pp. 667-677