Miyun Reservoir: Sword of Damocles Hanging Over Beijing
Miyun Reservoir: Sword of Damocles Hanging Over Beijing - If Miyun Reservoir’s dam breached, the resulting flood could submerge Beijing and neighboring areas.
Udumbara
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Torrential rains wreaked havoc in northern China in late July, with severe flooding exacerbated by large-scale reservoir discharges with high flow rates and minimal warning. At least 60 people have died, with dozens missing as of July 31.
The discharge from Miyun Reservoir, in particular, has caused significant damage.
With the excessive accumulation of water from the South–North Water Transfer Project’s central route in recent years, authorities have only considered the high water storage and reservoir levels as achievements, as water stored in the reservoir is sold for profit and creates a scenic attraction for tourism. They ignored the poor construction quality of the dam and its limited storage capacity.
Under the flood control priorities of the Chinese Communist Party (CCP), the primary objective is to prevent dam failures. But many dams are plagued by structural deficiencies, aging infrastructure, and insufficient maintenance, which prevent them from performing effectively. As a result, emergency or even unannounced discharges during heavy rains have become commonplace, despite previous promises made to locals.
If the main dam were to collapse, floodwaters nearly 7 feet high could reach Tiananmen Square in Beijing. To prevent such a disaster, authorities would quickly release large volumes of water to relieve pressure on the dam.
In response to continued inflow, starting on July 27, Miyun Reservoir began discharging downstream. By July 29, the total discharge had reached 6.35 billion cubic feet—equivalent to draining more than half the volume of Utah’s Deer Creek Reservoir in just a few days. With water rushing out at nearly 40,000 cubic feet per second—enough to fill an Olympic-sized swimming pool every two seconds—the torrent could easily overwhelm riverbanks, destroy crops, submerge roads, and pose a deadly threat to anyone living downstream.
In fact, it wasn’t just the Miyun Reservoir that discharged water. Reservoirs on the western, northwestern, and northeastern outskirts of Beijing also opened their floodgates, including the Baihebao, Yudushan, Haizi, Xiyu, Huangsongyu, Zhaitang, Zhuwuo, Luopoling, and Sanjiadian reservoirs.
2 Previous Reservoir Discharges
This is not the first time authorities have discharged Miyun Reservoir to protect Zhongnanhai, the CCP’s central headquarters in Beijing. In each instance of discharging, the areas near Beijing suffered significant losses.1st Discharge (1969)
Amid rising tensions following the 1969 Sino–Soviet border conflict, the Soviet Union allegedly planned to carry out devastating strikes, targeting cities such as Beijing and nuclear weapons facilities. To avoid catastrophic flooding if the dam were attacked, Chinese authorities discharged water from the Miyun Reservoir and evacuated top leaders and their families from Beijing—putting the lives of ordinary citizens at risk.2nd Discharge (1976)
The Tangshan earthquake in July 1976 severely damaged the Miyun Reservoir’s Baihe Main Dam. To prevent the dam from collapsing and to protect Beijing, authorities detonated a nearby hill to obtain rock for reinforcement. They also ordered an extended release of water from the reservoir. To alleviate pressure on the dam, emergency crews opened the gates to allow water to flow out. This discharge continued for more than two weeks until the reservoir was completely drained.
Miyun Reservoir
Miyun Reservoir, with a surface area of 72 square miles, is the largest of its kind in northern China. It is located in the northeastern suburb of Beijing, roughly 45 miles from the capital’s central business district.Initially built for multiple purposes, including flood control, irrigation, power generation, and aquaculture, the reservoir was not intended to supply drinking water to Beijing.
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Construction of the Miyun dam began in September 1958 and was completed in 1960. It was designed by Tsinghua University’s Department of Hydraulic Engineering, led by professor Zhang Guangdou.
Miyun Reservoir, South–North Water Transfer Project
Initially, Beijing’s drinking water was supplied by Guanting Reservoir and local groundwater. But over time, Guanting’s water supply dwindled due to the multiple dams built in the upper reaches of the Yongding River, which is the reservoir’s major source of water supply.Instead of addressing the root causes, CCP authorities reassigned Miyun Reservoir as Beijing’s main water source in 1982. At that time, Miyun’s water levels were low, and its storage was sufficient to handle heavy rains.
That changed in 2015, following the completion of the South–North Water Transfer Project’s central route in late 2014. This project is a massive infrastructure initiative designed to divert water from the water-rich Yangtze River in the south to arid northern regions such as Beijing through a system of canals, tunnels, and pipelines.
Each year, 35 billion cubic feet of water are diverted from the Yangtze River to Beijing. This diversion project has since taken over as the main water source for the city, replacing the Miyun Reservoir.
Yet, from 2015, Beijing began storing some of the diverted water in Miyun. Other local reservoirs, such as Huairou, Shisanling, and Yizhuang, also store diverted water.
The water from the south is first transferred from the Yangtze River to Beijing’s Tuancheng Lake, which is at a lower altitude than Miyun Reservoir. From there, the water is then pumped up to the reservoir via a 64-mile pipe network and nine pump stations that raise the water level by 436 feet.
Miyun’s water storage capacity was significantly boosted with the inflow of water transferred from the south, constantly breaking its own records over the years. In 2013, the capacity reached approximately 28.2 billion cubic feet. By 2018, this figure increased to 77.7 billion cubic feet.
As of July 29, 2025, the capacity soared to 128 billion cubic feet, with a water level of nearly 510 feet. This exceeds the 498-foot flood control limit for Miyun, the maximum water level set during the flood season to ensure adequate capacity for flood control. It appears that the CCP’s flood protocol was not enforced.
Miyun Reservoir sits more than 330 feet higher than Tiananmen Square. Like the Guanting Reservoir, it hangs over Beijing like a sword of Damocles.
If Miyun Reservoir’s dam breached, the resulting flood could submerge Beijing, Tianjin, Baodi, and Jixian.
