Are Jiuzhaigou's Lakes Blue Only Because They're Dyed? Officials Debunk the Rumor and Explain the Science Behind the Colors

Recently, a falsified video claiming that "Jiuzhaigou's lakes only appear blue because they are dyed with paint" has circulated online, misleading many tourists and tarnishing the scenic area's reputation. In response, the Jiuzhaigou Administration has issued a stern rumor-refutation statement, clarifying that the video was not even filmed at Jiuzhaigou, and that the online claim about dyeing is nothing but a baseless rumor.

A UNESCO World Natural Heritage site and World Biosphere Reserve, Jiuzhaigou's multicolored lakes are a natural geological and optical wonder, backed by solid scientific evidence, with no artificial coloring whatsoever involved at any stage. Sun Geng, a researcher at the Chengdu Institute of Biology of the Chinese Academy of Sciences, offered an expert explanation: the lakes' unique blue-green hue is shaped jointly by three factors — physical, chemical, and biological.

From a physical perspective, Jiuzhaigou's alpine lakes are exceptionally clean, with very low levels of suspended matter and plankton, giving the water extremely high transparency. Sunlight contains rays of red, orange, yellow, green, blue, indigo and more. Longer-wavelength light such as red, orange and yellow is easily absorbed by the water, while shorter-wavelength blue and violet light is more readily scattered — which is why the lakes show such vivid blue tones.

From a chemical perspective, the watershed's water is rich in ions such as calcium, magnesium and bicarbonate, which combine to form tiny travertine particles 0.1 to 0.45 micrometers in size. These particles efficiently scatter blue-green light, further enhancing the lakes' brilliant colors.

At the same time, aquatic organisms such as algae in the lakes produce secondary reflection of light, enriching the layered colors of the water.

Beyond these factors, differences in water depth, the changing of the seasons, varying weather conditions, and the viewing angle all cause the lakes to display gradient colors of varying shades, giving Jiuzhaigou its ever-changing, luminous waterscape.

The Jiuzhaigou Administration reminds netizens not to fabricate or spread false rumors that maliciously defame the reputation of this world natural heritage site. When confronted with short videos online, pay attention to distinguishing fact from fiction — neither believe nor spread rumors — and together help protect Jiuzhaigou's natural heritage and a clean online environment. For authoritative knowledge about the scenic area's natural landscapes, follow the official science-popularization content released by the administration.