The purposes and the types of dams in Al-Baha province, on the western south of Kingdom of Saudi Arabia KSA, are reviewed. Data are collected and tabulated ascending according to the capacity of storing water. The cost (in Saudi Riyal) is plotted versus the capacity (in m3) for the dams. Then a linear regression analysis is done employing micro soft excel software. An equation is obtained to predict the cost of dams with storage capacities less than or equal 500000 m3, where the type of dam has no effect on the cost. Also, taking into consideration the inflation rates along the time, the 2013's costs are estimated and another equation is obtained to predict the cost.