Assessment of Water Quality of Gurara Water Transfer from Gurara Dam to Lower Usuma Dam for Abuja Water Supply, FCT, Nigeria

Abstract

Water transfer from area of excess to area of scarcity is now becoming accepted option especially for regional water supply. The Gurara water transfer provides for the transfer of raw water from Gurara dam in Kaduna state to Lower Usuma dam in Federal Capital Territory (FCT), Abuja through a 75Km conduit pipeline to augment water supply to FCT as a result of rapid population growth. The purpose of the research is to provide baseline condition in term of quality of raw water at Gurara dam before the transfer and after mixing at Lower Usuma dam. Water Quality Index (WQI) was used to assess the quality of the waters for overall, drinking, aquatic, recreation, irrigation and livestock uses. Twenty (20) water samples from both dams were collected and some at predetermined depths and subjected to physicochemical analysis using APHA standard methods of analysis for both wet and dry seasons. The overall WQI was poor. The WQI was poor for drinking and aquatic, but fair for recreation and livestock, and good for irrigation. These were due to high concentration of COD, BOD, total hardness, turbidity, Ca, K, Mg, Cd, Pb and Fe. The results of the analysis when compared with the Nigerian Standard for Drinking Water Quality (NIS 544:2007) and World Health Organization (WHO) permissible limits showed that the Gurara dam and Lower Usuma dam were polluted and that the water was not safe for drinking. Variations in the constituents concentration in terms of water depths and seasons were observed. Regular monitoring of the water quality should be carried out as the watershed is presently rural but faces potential urbanization in the coming decades.