Abstract
This paper aims to examine the historical change in the newly developed water resources of Koi breeding ponds in the Higashiyama area of the Ojiya City and the Old Yamakoshi Village. It was clarified that the development of new water resources and the introduction of large pond construction techniques accounted for the rapid increase in the number of Koi breeding ponds after the 1960s. The development of water resources is divided into the following eight stages. 1) before 1945; Koi were bred together with food carps in traditional style, 2) after 1945; breeding ponds were converted from paddy fields under worse production condition, 3) after the mid-1960s; large-scale irrigation ponds in plains were used for breeding Koi, 4) after the 1970s; breeding ponds were converted from paddy fields as a result of the rice production adjustment policy, 5) after the mid-1970s; breeding ponds fed by snowmelt and rainwater were being constructed, 6) after the 1980s; existing breeding ponds were borrowed or bought, 7) after the 1990s; large-scale irrigation ponds in plains were used again for breeding Koi, 8) after 2005; groundwater was pumped up from wells for breeding ponds.
