By the mid-17th century, the Ohori Moat, formed by reclaiming and dredging a large cove at the time of castle construction, was filled with sediment and the Torikai area was drained and turned into grassy land. Accordingly, during the period of Empo (1673–1689), the area that was turned into land was developed into rice fields, and the Odote Causeway was built along the shorelines. At the same time, the Komo River was modified to flow on the west of the Odote Causeway so that the silt in the flows would be carried to the sea by the river. After these works, the dimensions of the Ohori Moat were reduced; the water surface was however still more than twice as large as the present Ohori.