In this research, a case study was conducted in Edogawa-ward in order to identify the change of river and waterway functions and water activity projects as a result of urbanization in Tokyo metropolitan area. Recently some agricultural irrigation canals have been either filled in or converted into drainage ditches, other canals have been reconsidered as a precious natural resources to be utilized for the improvement of urban environment. In this research, first, historical changes for the water supply are examined in relation to agricultural activities. Second, the transition of agricultural irrigation canals, which at first was covered to an urban sewage drainage after the dissolution of irrigation associations examined to identify how the Edogawa-ward municipality re-converted the canals into the water activity facilities, based on the background of city planning process. The canals were once severely polluted due to the construction delay of sewage lines, however, the municipality has made and effort to improve the canals to be utilized as water activity facilities, recommended by the municipality's master plan. There have been much activities going on at the canals since then, and several groups have been organized to protect the canals' environment.