Physicochemical Properties of River Otamiri being Impacted Rainwater Runoff Discharge from the Adjacent Nekede Ihiagwa Dumpsite, Imo State, Nigeria

Open waste dumps remain one of the most common waste disposal methods in Nigeria. These sites which are usually uncapped allow contaminated rainwater runoff which poses high risk to nearby sensitive water receptors. An investigation was undertaken to ascertain the physicochemical sensitivity of River Otamiri to pollution loading due to contaminated rainwater runoff discharge from the adjacent Nekede Ihiagwa dumpsite, Imo State, Nigeria using appropriate methods. Mid and downstream water samples recorded significantly elevated concentrations of key dumpsite leachate indicators above assessment and guideline limits peaking at 8 mg/l O2 (BOD), 87 mg/l O2 (COD), 3.4 mg/l (NH4-N), and 42 mg/l (Cl). Conversely, lower concentrations of upstream control point values were note mostly below or at assessment and control limits peaking at 5 mg/l O2 (BOD), 52.4 mg/l O2 (COD), 2.1 mg/l (NH4-N), and 30 mg/l (Cl). Seasonal variation in surface water quality was also noted with higher concentrations of all parameters noted in the dry season indicating that dilution was likely occurring during the rainy season. The study highlighted the urgent need for the implementation of remedial measures such as the installation of a clay cap and a leachate collection and treatment system at Nekede-Ihiagwa waste dumpsite to mitigate the associated ecological and public health risks.