On this day, 71 years ago, on May 13, 1954 (April 11, 1954, the lunar calendar), my country's first large-scale valley reservoir-Yongding River Guanting Reservoir was completed and put into operation. Location map of Guanting Reservoir On May 13, 1954, the completion ceremony of my country's first large-scale valley reservoir-Yongding River Guanting Reservoir was held. Guanting Reservoir has a reservoir capacity of more than 2.2 billion cubic meters. It is located in the basin at the junction of Yanqing County in Beijing and Huailai County in Hebei Province. It covers an area of 230 square kilometers and has a total water storage capacity of 2.2 billion cubic meters. The reservoir dam was built between the two mountains to cut off the Yongding River. The completion of the reservoir not only reduced the flood peak flowing upstream during the flood season, but also intercepted a large amount of sediment, allowing the Yongding River to be completely eradicated. Mao Zedong once visited Guanting Reservoir in person and wrote an inscription: "Celebrate the successful completion of the Guanting Reservoir project." After the reservoir was completed, it has always played a huge role in flood control, power generation, irrigation, water supply and other aspects.