Hong Kong's Wenhui Daily reported a high-profile chemical incident that took place on the evening of November 28, 2005. The Guli Security Products' steel plating galvanization fluid leaked approximately 500 liters (132 gallons) of chemicals, including 12 kg (26 pounds) of highly toxic hydrogen cyanide, into the adjacent city sewer system of Zhongshan County. From there it flowed into Xiaolan Township. The authorities did an emergency shutdown of the water gates and then poured 100,000 tons of sodium hypochlorite into the river to dilute the concentration of cyanogen. The cause was sited as aging facilities. The authorities announced that water quality was restored to normal levels and no one was harmed, in any way.
The factory didn't notice the leak of the galvanizing fluid until the following morning. Although people were sent to take water samples immediately, the river waters in Xiaolan Township had already been polluted. The company reported to the municipal environmental protection administration and other related agencies right away.
Zhongshan City government took contingency measures immediately by shutting down all the water gates to the main rivers in Xiaolan Township to prevent the spread of the pollution. After dumping 100,000 tons of sodium hypochlorite into the rivers to reduce the concentration of cyanogen, they opened the water gates twice a day during high tide to further dilute the pollution in the rivers.
On November 29, water quality in these rivers began to gradually return to normal levels. The polluted water was released into the ocean via the Shiqi River in Zhongshan County. On November 30, the water quality returned to normal levels completely. However, the news about this incident was simply reported by electronic mass media in Zhongshan City's Xiaolan Township.
The report quoted Zhan Genxiang, deputy director of Zhongshan Municipal Environmental Protection Bureau, as saying that the pollution is currently under control and contingent measures are to be removed in the afternoon of December 5, 2005. This incident has not affected the source water or the Pearl River Basin; nor have any humans or livestock been poisoned.