Selecting the Nabari-gawa River from a short list, the Construction Ministry made a plan to build Tsukigase Dam over the main stream of the Nabari-gawa River and Udagawa Dam (later Muro Dam) over the Uda-gawa River, and started a preliminary study of these sites as the 'Comprehensive Development of the Upstream Area of Kizu-gawa River' in 1952.
この中で名張川が着目され建設省は名張川本川に月ヶ瀬ダムを、宇陀川に宇陀川ダム（後の室生ダム）を建設する計画を立て、「木津川上流総合開発事業」として1952年（昭和27年）より現地点での予備調査に着手した。