Reports in the Chinese media indicate that pollution in the Songhua river has long been a source of friction between the neighbouring provinces of Jilin and Heilongjiang.
The river flows from Jilin past Harbin in Heilongjiang.
Zhai Pingyang, a senior environmental official in Heilongjiang, told the Harbin-based newspaper Life Daily (Shenghuo Bao) he believed that
most pollutants in the river came from the Jilin plant run by the China National Petroleum Corporation, where the blast that led to the toxic spill occurred.
Mr Zhai said that ever since it was built in the 1950s, the company had been "inseparably linked" to a drop in the quality of the river water.
Liu Yuzhu, a top official at the Harbin Water Company, said that three days after the Jilin blast which led to the release of poisonous chemicals, Harbin had "quietly" sent a team of environmental officials and water company staff to Jilin to collect water samples from the upper reaches of the river.
"We have dealt with the Jilin side countless times. Every time the river was polluted, Jilin, which is on the upper reaches, issued reports that no pollution was found in their waters. Countless interactions have led to countless confrontations," Ms Liu told China Newsweek (Zhongguo Xinwen Zhoukan).
Whenever the central government sent an investigation team, she added, Jilin would put the waste water treatment plant into operation. But as soon as the team left, officials would shut the plant down again to save costs, she alleged.
"This time, in order to get first-hand information about water quality quickly, we followed up the incident and collected samples from the very beginning."
View from Jilin
Officials in Jilin think differently.
An unnamed source at the Jilin city Communist party committee told First Financial and Economic Daily (Diyi Caijing Ribao) that Harbin had tried to "make an issue of water pollution" for many years.
He said it remained to be seen whether the city's water stoppage was directly attributable to the Jilin blast.
The paper added that when first asked about the pollution, Jilin provincial party officials had denied they had heard of it, while the company had said at first that the explosion had only produced carbon dioxide and water.
The provincial daily Jilin Ribao reported Vice-Governor Li Bin as saying that local officials had taken "effective measures and went all out to control the damage" following the blast at the plant.
"Because the guidance and coordination were forceful and orderly and the emergency preparatory plan was relatively comprehensive, all prevention and control measures were implemented and put in place rapidly and effectively," Mr Li said.
He added that the provincial government had "informed the relevant state department and the neighbouring province of the situation in a timely manner".
But China Youth Daily quoted an unnamed engineer in the Jilin environmental protection department as saying that the Jilin authorities had found out about the pollution on the day the blast occurred.
The paper said it had contacted the company but it had refused to comment, while city and provincial officials had in their turn passed the buck, deferring to the central authorities.
China Newsweek (Zhongguo Xinwen Zhoukan) said the incident should serve as a "wake-up call" to the government.
"The central government should start trying to establish a long-term and formal mechanism to coordinate the interests of different provinces," it said.
"The unclear responsibilities of different levels of government and the lack of institutionalized coordination mechanism between them have exposed the public to chemical pollution, but the government finds it difficult to do anything about it."
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