The purpose of this thesis was to evaluate the physicochemical and bacteriological waterrnquality aspect of Lake Ziway in relation to Fish Farming. On global scale waterrnpollution, i.e. microbial water pollution, pose the greatest problem. Chemical pollution isrnalso of a great concern.rnTwenty grab samples from twenty sampling site ten from the surface and ten from thernbottom were collected using Kemmerer volume sampler. A total of sixty samples wererncollected and analyzed for physicochemical, bacteriological, and heavy metal usingrnstandard methods.rnCOD result showed a maximum value of 3500mg/l and minimum value of 110 mg/l.rnSimilarly BOD5 ranges from189.81mg/l to 8.57 mg/l. The temperature of this lake is inrnbetween 20 and 23 oC. Dissolved Oxygen is found to be 6.7 to 10.05 mg/l. The lake isrnwell-oxygenated, which a sign of healthy lake. At almost all sampling sites NH3 is greaterrnthan 0.4 mg/l. The minimum value of Turbidity, Total Solids, and Total dissolved Solids,rnand Electrical Conductivity is 62mg/l, 356 mg/l, 251 mg/l and 251 m s/cm, while thernmaximum value is 596mg/l, 462 mg/l, 304 mg/l, and 458 m s/cm, respectively. The pH ofrnLake Ziway is nearly alkaline (with a pH greater than 8 in almost all sample sites). TN isrnfound to be greater than TP. The concentration of (Chloride) Cl- is similar along the lakesrnin all sample sites with a value greater than 14mg/l in all sites being sampled. The rangernof concentration of heavy metals such as Cd, Cr, Zn, Pb, Al, Mn, Ni, and Cu is,rn0.3538mg/l, 0.295mg/l, 0.0083mg/l, 0.636mg/l, 1.862mg/l, 0.0828mg/l, 0.0018mg/l, andrn0.0012mg/l respectively.rnThis study indicated that, there is an increment of nutrient input into this fresh lakernsystem. This may result in the Eutrophication of the lake and consequently deteriorationrnof the water quality in the future. Hence, urgent action is required for the sustainable usernof the Lake, before its quality goes behind the turning point