Spatio-Seasonal Assessment of Water and Sediment Quality of the Imiringi River and Implications for Fisheries and Aquatic Resources in the Niger Delta

Rivers in the Niger Delta play a critical role in supporting agriculture, fisheries, livestock watering and rural livelihoods, yet increasing anthropogenic pressures continue to degrade their quality. This study evaluated the seasonal and spatial variations in water and sediment quality of the Imiringi River, Ogbia LGA, Bayelsa State, with emphasis on implications for agricultural water use and aquatic productivity. Sampling was conducted at three stations upstream (S1), midstream (S2) and downstream (S3) during the wet and dry seasons. A total of fifty-four water samples and fifty-four sediment samples were collected and analysed using APHA (2017) standard methods, with in-situ measurements obtained using calibrated multiparameter instruments. Results revealed a progressive downstream deterioration in water quality across both seasons, with higher turbidity, nutrients, organic load and microbial indicators at S3, particularly during the wet season due to surface runoff and domestic waste inputs. Dissolved oxygen declined downstream, suggesting reduced suitability for fish survival and aquaculture activities. Although dissolved heavy metals (Pb, Cd, Cr, Ni, Cu, Zn, As and Hg) remained below WHO guideline limits, their consistent downstream increase, together with elevated sediment metal concentrations approaching probable effect level (PEL) thresholds, indicates potential risks of bioaccumulation in fish and livestock exposure through water use. Microbial contamination far exceeded drinking-water standards, rendering the river unsafe for irrigation of fresh produce, livestock watering and domestic use without treatment. Water Quality Index (WQI) analysis classified the upstream station as good to fair, the midstream as fair to poor, and the downstream section as poor to very poor in both seasons, confirming declining water suitability for agricultural, fisheries and livestock purposes. These findings highlight the need for integrated watershed management and community-based pollution control to safeguard food production systems and aquatic resources in the Niger Delta.