Fecal coli forms were observed by CORPOURABÁ in distinct seasons of the year in the Golfo de Urabá, in places relatively far from possible costal sources, having into consideration the degradation rate for pathogenic micro flora that is order of hours. The objective of this paper was to determinate the scales of coli forms pollution extension with the origin in point sources in the principal rivers and urban zone. With the aim of studying coli form dynamics in the gulf, a hydrodynamic model ECOMSED was applied. The substance transport was simulated as well in lagrangian as in eulerian systems. With the first one, spatial dispersion from each one of the sources was identified; with the second, resulted contamination patterns were established for different climate conditions.