One May day in 1956 when President Kim Il Sung came to look round the Phyongnam irrigation facilities, officials asked him to name a reservoir.
Saying that it is advisable for the builders to name the reservoir, Kim Il Sung suggested them to give a good name to the reservoir by pooling wisdom. Saying that the Yoltusamcholli Plain will have a bumper crop every year with the completion of the Phyongnam irrigation project that can be called the “eldest son” in the irrigation of the country, Kim Il Sung suggested to name the reservoir Yonphung.
As a result, reservoir was named Yonphung.
