Tannery effluents are complex discharges, highly loaded with organic and mineral matter, especially chromium. They have variable characteristics and biodegradability over time. In this study, the concentrations of total heavy metals, especially total Cr in tannery wastewater samples, were successfully determined by the ICP-AES technique. The excesses of total metal concentrations indicate that the studied waters were so polluted considering the total concentration. This pollution causes various serious negative environmental effects, which are carried out on the human body through the food chain. The speciation of metallic elements in tannery discharges remains very interesting to prevent the action plan to reduce the pollution of these discharges. The speciation results indicate that most analyzed metals are abundant in the particulate phase. The percentage of Cr, Cu, Pb, Hg, and Ni in the dissolved phase is of the order of: Cr: 0.05–8%; Cu: 7.1–47.2%; Pb: 4.4–50%; Hg: 2–11%, Ni: 0–14%. Meanwhile, cadmium presents a much more significant fraction: Cd: 60–100%. The presence of metals in particulate form follows the following decreasing order: Cr > Ni > Hg > Cu > Fe > Pb > Zn > Cd. The observed changes in the physical speciation of trace metals highlight the importance of distinguishing the permeable phase (truly dissolved) from all dissolved species to better assess environmental releases. However, traditional laboratory methods do not separate colloids from the dissolved phase. Such a lack of separation between the colloidal and permeable fractions can lead to inaccuracies in the results of studies on the fate and behavior of contaminants in the aquatic environment. This fraction should be the subject of particular interest to arrive at a better ecotoxicological assessment of releases into aquatic ecosystems. Determining the total concentration of a potentially toxic element provides little information on its actual toxicity. Indeed, the toxicity of an element is directly linked to the chemical form in which the element is present (and therefore to its speciation). Indeed, the absorption rate by the human body is often directly linked to the chemical form and, in particular, to the solubility of the chemical species considered. These results contribute to the project to monitor the quality of tannery water in Mohammedia, whose work is continuing in order, in particular, to assess the environmental impact of tannery discharges into the environment.