Assessment of the physico-chemical properties of Oguta Lake compared to the established values of the Federal Ministry of Environment, Nigeria

Constant assessment of physical and chemical parameters in freshwater ecosystems is largely recommended. This is even more important when water resources, e.g. lakes in most countries, serve as a source of water for domestic and commercial purposes, and /or when freshwater ecosystems represent a refuge for most aquatic organisms. In this paper, we investigated the physical and chemical properties of water resources at three sampling stations of Lake Oguta, comparing the weekly values (June-July 2018) with the water quality standard established by the Nigerian Federal Ministry of Water Resources (FMWR). The parameters analysed included water temperature, pH, dissolved oxygen (DO), chemical and biological oxygen demand (COD, BOD), potassium, magnesium, sodium, calcium, phosphate, nitrate, chloride and sulphate. Most of the cations (calcium, magnesium and sodium), anions (phosphate, nitrate, chloride and sulphate), as well as water temperature, BOD and DO were below the quality standard limits. The basic chemistry and temporal variations may have been caused mostly by natural factors such as geology, topography, meteorology, hydrology, water levels and biological activity. Being in line with the recommended standard levels, the nutrient concentrations, pH and hardness in the current study may indicate favourable conditions for the life of aquatic organisms and contemporary co-existence with the human exploitation for drinking purposes. Nevertheless, to assure a safely and conscious exploitation of this water resource, we recommend continuity in the monitoring studies. To assure an accurate evaluation of the physical and chemical parameters, future studies should include a larger sample size and extended study periods (including other seasons).