This study was carried out on River Atuwara in Ota, Ogun State, Nigeria with the aim of developing a coefficient of re-aeration model applicable to River Atuwara and other rivers in the Nigerian environment. This was achieved by sourcing for data once every month from 22 sampling locations within a pre-selected segment of the river over a period covering the dry and wet seasons. Data collected include hydraulic and water quality data (Dissolved Oxygen and Biochemical Oxygen Demand). Excel Spreadsheet and MATLAB were used for data processing. Regression analysis was also carried out. A coefficient of re-aeration (Atuwara model) was developed and validated statistically. Its performance was also checked by comparing it with ten other well cited models. It was found that Atuwara model and Agunwamba model could be safely adopted for future water quality modelling researches in the Nigerian environment. Results of detailed water analysis of samples from River Atuwara show high level of pollution hence it is unfit for human consumption without adequate treatment. It is recommended that River Atuwara and similar rivers in the country should be regularly monitored for quality control.