Dam construction has long provided valuable economic benefits to Thailand in distributing low-priced electricity and supporting low-income farmers by providing them with free-flowing irrigation water; this promotes domestic consumption and investment. Even though many benefits are expected from dam construction, a dam project needs to be carefully evaluated using cost-benefit analysis (CBA) before approval. Decision-makers have to review the negative effects of the construction and operation of a dam. These effects are sometimes difficult to measure in monetary terms.