The objective of this study is securement of upland irrigation water using storage level management of small dams. However, it is not new development of water resources but securement of water using storage level management of existing dam. This study has enhanced the water utilization coefficient of dam, after extra available water had been calculated by application of periodical management storage level and this water is used to other water like the upland irrigation water demand. As the result of application, it can secure extra available water except the water requirement. Minimum extra available water except flood is about $20,000,000;m^3$ and crop irrigation water demand of 10yr frequency is about $2,033,000;m^3$ in Seongju. The utilization of crop irrigation water can be possible. And extra available water is about $3,102,000;m^3$ in 2000, $1,959,000;m^3$ in 2001 except flood period and crop irrigation water demand of 10yr frequency is about $2,272,000;m^3$ in Donghwa. It is judged that extra available water cannot be used to crop irrigation water during the dry season in Dongwha. Consequently, when management storage level is determined and more efficient use of water is gotten like this study, water utilization coefficient will be enhanced.