Before the liberation, the Pothong River in Pyongyang had been known a disastrous one taking a large number of lives while flooding villages and fields in rainy season.

Taking to his heart the sufferings of people living alongside the river, President Kim Il Sung determined to start the grand nature-transformation for building a prosperous, independent and sovereign state with the Pothong River improvement project as the first, and aroused the people to the project.

He attended the ground-breaking ceremony for the river improvement project on May 21, Juche 35 (1946) and made an encouraging speech. In his speech, he said that success or failure in building a new democratic Korea totally hinges on the people's own efforts and they should complete such projects as the Pothong River improvement project one after another by their own efforts though they have to tighten their belts. And he added that the river improvement project should be done by the Korean people themselves without any help from others and they should overcome all difficulties on their own efforts.

Cherishing deep in their minds the spirit of self-reliance the President implanted in them while breaking ground first to signal the start of the river improvement project, the people turned out as one in this patriotic nature-remaking project. They removed 420,000 cubic meters of earth and built five kilometer-long embankment, thus finishing in 55 days the project which the Japanese imperialists failed to do for ten years even though they had mobilized three millions of people by force.

With the completion of the project, the river came to flow into the Taedong River through a new waterway and the banks of the Pothong River be free from flood damage forever.

The completion of the Pothong River improvement project was the first achievement the Korean people made in building the democratic capital city by their own efforts under the leadership of Kim Il Sung after the liberation of Korea.