From 1997 irrigation water withdrawals has been surveyed for the purpose of river operation and management. Recently, the River Law was revised(1999. 2. 8) and obligate to water users to report their proposed and actual water withdrawals. If we can save more water from rice paddy area, we can use more water for municipal and industrial activity, and we can expect water quality should be improved in the river. So the role of irrigation water use efficiency is more and more important.