Researchers and residents have given a guarded welcome to a government regulation to curb pollution of the Songhua River, which took effect on Friday.
It gives Jilin provincial and city authorities the power to suspend the production of polluting factories.
They also face fines of between 100,000 ($14,600) and 200,000 yuan for failure to meet environmental protection requirements.
"Sheer punishment is not enough. Factories need to be made aware of the harmful effects of pollution. Education is one way," Bing Zheng, president of Jilin provincial academy of social sciences, said.
He recently conducted a study of Songhua River's water quality.
Jilin legislators first considered such a regulation in 2005, when an explosion at a factory caused 100 tons of toxic chemicals to spill into the river.
Harbin, Heilongjiang province, a city of nearly 4 million people, was forced to suspend its water supply for about four days.
"I grew up on the banks of the Songhua River; we depend on it for drinking water. I hope the water will once again be clear as it used to be," local man Zhang Qi said.
Jilin province is home to many large chemical plants located near the river. The government has been under constant pressure for years to clean up the river.
"Many new problems have emerged in recent years," Wang Guocai, director of Jilin provincial bureau of environmental protection, said.
He said a number of factories had failed to take any action to address the problem, and others are being built without going through environmental evaluation.
The new regulation requires all factories that discharge wastewater to install automatic monitoring devices, wang said.
"We will be able to guarantee our sewage discharge meets the specified standard," Chu Laning, general engineer of the Changchun Dacheng Group, said.
It is the biggest producer of lysine and one of the top three corn processors in the country.
Eighteen new sewage treatment projects are under construction, Zhu Yanfeng, vice-governor of Jilin province, said.
The Songhua River flows more than 1,900 km from Mt Changbai through Heilongjiang and Jilin provinces.
Source: China Daily