This study presents a comprehensive evaluation of the Ramshar Wastewater Treatment Plant (WWTP) and assesses the suitability of its treated effluent for agricultural and green space irrigation applications. Five physicochemical water quality parameters—biochemical oxygen demand (BOD5), chemical oxygen demand (COD), total suspended solids (TSS), electrical conductivity (EC), and pH—were monitored over a 12-month period and analyzed through an integrated framework combining descriptive statistics, regulatory compliance assessment, and probabilistic risk modeling using a 100,000-iteration Monte Carlo simulation. The treated effluent demonstrated stable and favorable quality characteristics, with mean concentrations of 34.83 mg/L (BOD5), 55.83 mg/L (COD), 16.83 mg/L (TSS), 500 µS/cm (EC), and a pH of 7.82—all substantially below the corresponding national limits for agricultural irrigation under Iranian Standard No. 2901. Full compliance (100%) with agricultural reuse standards was achieved across all monitored parameters. For green space irrigation, all parameters except BOD5 consistently satisfied the more stringent regulatory thresholds. While COD, TSS, EC, and pH exhibited zero probability of exceedance in the Monte Carlo simulation, BOD5 displayed a 19.41% probability of exceeding the 40 mg/L limit, reflecting moderate seasonal and operational sensitivity inherent to the biological treatment process. Notwithstanding this variability, overall effluent quality remained within acceptable ranges for landscape irrigation under most operational conditions. The integration of deterministic and probabilistic analytical approaches provides a robust understanding of effluent reliability, underscoring the WWTP’s strong performance and operational stability. The findings confirm that the Ramshar WWTP constitutes a dependable source of reclaimed water for agricultural irrigation, with generally favorable potential for green space reuse, and indicate that targeted optimization of biological oxygen demand removal could further enhance compliance under stringent reuse criteria.