Turkish Journal of Fisheries and Aquatic Sciences
2008, Vol 8, Num, 2 (Pages: 309-319)
Assessment of the Water Quality of Oyun Reservoir, Offa, Nigeria, Using Selected Physico-Chemical Parameters
Moshood Keke Mustapha 1
1 University of Ilorin, Department of Zoology, Pmb 1515, Ilorin, Nigeria
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The variations in selected physico-chemical factors were investigated for two years to determine the water quality of
Oyun Reservoir, Offa, Kwara State, Nigeria for drinking and fish production. Three stations were chosen on the reservoir to
reflect the effect of human activities, lacustrine and lotic habitats. Temperature, transparency, pH, conductivity, total
dissolved solids, dissolved oxygen, nitrate, phosphate, chemical oxygen demand, total alkalinity, total hardness, calcium,
magnesium, silica, sulphate, carbon dioxide were analyzed monthly between January 2002 and December 2003 using
standard methods and procedures. The ranges of these factors were found to be comparable to those reported for other
African reservoirs except for nitrogen and phosphate which were found in higher concentration above freshwater limits. Runoff
of nitro-phosphate and sulphate fertilizers from nearby farm lands and washing of cows dungs from the watershed into the
reservoir were found to have caused cultural eutrophication in the reservoir. The eutrophication was pronounced at Station 1
due to impact of human activities on the watershed, and with time, it will affect the water quality and fish production in the
reservoir. The study concludes that Oyun reservoir has excellent water quality, high ecological status and passes chemical
status. Eutrophication which was noticed to be a threat to the water quality should be arrested at the nick of time through
denitrification and nutrient control to halt the degradation of the water.
Keywords :
Eutrophication, Fertilizers, Ecology, Total Dissolved Solids, Fish production