Suitability Assessment of Water Quality of Assabol Dam for Irrigation, Fish Culture and Drinking Purposes at Erob Wereda, Eastern Tigray; Ethiopia

The present study aimed at assessing the suitability of Assabol flood water harvesting dam for irrigation, fish culture and drinking purposes by evaluating its physical, chemical and bacteriological qualities and selected heavy metals (Co, Cd, Pb, Cu and Zn) concentrations. Composite surface water samples in triplicates were collected from the dam at various sampling points and analyzed using standard methods. The laboratory results of this study revealed that total hardness (182.8+0.20, 189.8+0.25, 193.8+0.36 mg/l), ammonium (0.31+0.02, 0.37+ 0.01, 0.38 +0.01 mg/l), alkalinity ( 135.2+0.28, 140.77+0.25, 140.93 + 0.81 mg/l) and total coliform ( 2.1x105, 2.06x105, 2.20x105 CFU/1000ml) as well as lead, (0.078+0.03, 0.07+0.01, 0.078+0.02 mg/l) concentration for the sample sites AS1, AS2 and AS3 respectively exceeds the permissible limit of WHO standards for drinking purpose. Results of analyzed irrigation parameters such as, Sodium Adsorption Ratio (0.46, +0.02, 0.48+0.01, 0.04+0.06meq/l), Residual Sodium Carbonate (-1.35+0.03, -0.75+0.05, -0.72+0.041meq/l), Electrical Conductivity (490.2+0.31, 482.10 + 0.12, 523.33 + 0.29s/cm) and specific ion toxicity (Na %, 15.3+0.01, 17+0.03, 17.3+ 0.02, Cl-, 2.19+0.13, 2.2+0.04, 2.34+0.03meq/l) including ( PH, 7.8+0.10, 8.10 + 0.21, 7.9+0.11, HCO3-, 2.6+0.01, 2.95+0.04, 2.93+0.02 meq/l) for the three sites respectively were also found to be within maximum permissible limit of FAO 1985. Chloride concentration might be toxic to Cl- sensitive crops even if its values lie within the range of permissible limit. The concentrations of heavy metals fall within allowable limit of FAO1985 except Cu concentration. Similarly, physical, chemical and bacteriological parameters of Assabol flood water harvesting Dam found to be within a permissible limit indicating its suitability for aquaculture activities. The findings from this study revealed that Assabol flood harvesting Dam water need proper treatment before it is used for drinking and irrigation purposes, while the water is safe for fish culture activities. The study also shows there is a need for watershed management, regular surveillance and water quality monitoring for the safe and sustainable use of the dam water resource in the locality.