The wastewater treatment plant of Settat city uses the natural lagooning technology, which requires low maintenance cost and little technical expertise. The purpose of this study was to evaluate the stability of plant performance during two years of operation (2019 and 2020), as well as the safety of its treated wastewater for reuse in agricultural irrigation. The results of this study show that the biochemical oxygen demand (BOD5), chemical oxygen demand (COD) and suspended solids (SS) did not exceed the Moroccan standards for discharge. They also show a good stable pollutant load reduction with a mean of 86.44%, 86.89% and 74.61%, for BOD5, COD and SS, respectively. On the other hand, microbiological characterization classifies the treated wastewater as “B” quality water, because the fecal coliform numbers exceed the requirement for “A” quality (1000 CFU/100 ml).