Detailed sedimentary facies and depositional environment studies were carried out on clastic deposits outcropping around Opi and its environswithin the Ajali and Nsukka Formation of the Anambra Basin. This defines the depositional facies, and sandstone hydrodynamics. The results revealed sixlithofacies which are systematically recognized into four genetically connected facies associations based on the textural parameters and diverse sedimentary structures derived from the hydrodynamic controls. The sedimentary facies include Structureless sandstone facies, Heterolith facies, Mudstone facies, Wave ripple facies, Parallel laminated sandstone facies and Planar Cross bedded Sandstone facies with its respective structural elements pivotal in the qualitative and quantification of the lithofacies and facies association description. The facies associations systematic paleo-environment diagnosis reveals depositional in fluvial, upper shoreface to lower shoreface depositional settings. The sandstones are predominantly medium to coarse grained and poorly sorted, indicating high-energy depositional conditions. Furthermore, their symmetrical skewness suggests the depositing medium operated at a steady velocity over a prolonged period, a characteristic feature of fluvial systems.