This study aims to investigate the barriers to the development of water-based tourism in Ahvaz and examine the mediating role of river environmental quality. The study is applied in terms of purpose and descriptive-analytical in terms of nature. The statistical population consisted of citizens aged 20 years and older in Ahvaz. Using Cochran’s formula, a sample of 383 respondents was selected. Data were analyzed using statistical tests, including the Kolmogorov–Smirnov test, confirmatory factor analysis (CFA), and structural equation modeling (SEM), using SPSS and SmartPLS software. The mediating role of river environmental quality was examined using the bootstrapping method. The results indicated that the measurement model had an acceptable fit and satisfactory validity and reliability. The findings showed that five groups of barriers—including institutional-managerial, environmental, physical-spatial, economic-investment, and socio-cultural barriers—had significant negative effects on the development of water-based tourism in Ahvaz. Among these, environmental barriers, with the highest path coefficient (-0.200), were identified as the primary impediment. Furthermore, river environmental quality, with a path coefficient of 0.480, was identified as the most important driving factor and was found to have a partial mediating role in the relationship between barriers and water-based tourism development. The results indicate that the development of water-based tourism in Ahvaz requires an integrated approach involving continuous environmental monitoring, riverbank management, improved safety, and greater participation of the local community.