Sediments from wastewater treatment plant sites are significant reservoirs of pollutants that can disrupt ecosystems. This study focused on assessing environmental pollution by trace metals, primarily originating from wastewater, in the Beni Mellal Khénifra region of Morocco. Sediment samples were collected along the 0-25 cm horizon every two months throughout 2022 at three sites: Beni Mellal (BM), Azilal (AZ) and Khouribga (KH). Analyses were conducted by using inductively coupled plasma atomic emission spectrometry (ICP-AES). Sediment quality was evaluated by calculating several indices: the contamination factor (CF), the enrichment factor (EF), the geo-accumulation index (Igeo), the pollution load index (PLI), and the potential ecological risk index (RI). The results showed that the average abundance of metallic elements in the sediments followed the order: Fe > Zn > Cr > Cu > Pb > Ni > Cd. Significant spatio-temporal variations were also observed for all metallic elements except Zn. The calculation of various pollution indices (CF, EF and Igeo) revealed a strong anthropogenic contribution of Cd et all three sites, of Zn et the KH site, and of Cr at both the KH and AZ sites. Multi-element indices (PLI and RI) qualify the sediments as polluted and may present an ecological risk in the following order: KH > AZ > BM. The strong correlation between most of the trace metallic elements at the BM and AZ site suggests a similar origin. These findings indicate that sediment contamination is influenced by the nature and intensity of anthropogenic activities specific of each province of the region. Agricultural and mining activities were identified as the main sources of these elements.