In this study, it is aimed to calculate the water budget of Lake Uluabat to cover from August 2013 to July 2014, one of the important shallow lakes that Turkey has. The lack of regularly measured data is the biggest problem in calculation of water budget of the lake. A lake water budget is computed by measuring or estimating all of the lake`s water gains and losses and measuring the corresponding changes in the lake volume over the same time period. Recharge of the lake is supplied from especially precipitation, drainage, surface and subsurface water inflow. The discharge components of the lake are evaporation and water intake for irrigation. The absolute difference between recharge and discharge of the lake was calculated as 53.2 hm3 for 2013-2014 water year period. The relative error was found 4.4 hm3. In general, this situation shows that there are illegal water catches in the lake or that the lake feeds underground water.