An algae bloom, not chemical pollution, was to blame for red and foamy water in parts of a major river system in central China, environmental officials said Thursday.
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The algae bloom stemmed from an abrupt rise in temperature, low water levels and slow currents, according to an announcement on Web site of the Hubei provincial environmental bureau. While some types of algae can produce dangerous toxins, the announcement said this bloom was harmless, though it has a fishy smell.
While the official explanation addressed the direct cause of the water contamination, algae blooms themselves are frequently blamed on pollution from factories and sewage a process known as eutrophication that saps water of oxygen and makes it dangerous to drink.
Tests had shown the river water had elevated levels of ammonia, nitrogen and permanganate, a chemical used in metal cleaning, tanning and bleaching, the government's Xinhua News Agency had said. But the environmental bureau said the chemicals did not cause the algae bloom.
Last summer, pollution was blamed for an explosion of blue-green algae on China's largest freshwater lake, Lake Tai, near Shanghai, forced the cutoff of tap water to millions of residents.
Water from nearby Lake Chang was being diverted to flush away the algae, and tap water was gradually being restored to residents, the environmental bureau said. It did not say how many people were still without water.
The water stoppage had forced residents to turn to emergency supplies such as bottled water and limited underground sources. Several schools were closed.
Environmental regulators say the majority of China's waters are so polluted that tens of millions of people have no access to clean drinking water. In a report released last week, the State Environmental Protection Administration said several tributaries of the Yangtze and surrounding areas in Hubei have seen their water quality deteriorate, despite an ambitious plan to reduce pollution.
