China will endeavor to eliminate most black and odorous water bodies in urban areas by the end of 2025, according to a recent action plan.

Before June, all county-level cities should hammer out and make public their treatment plans for all such heavily polluted water bodies, specifying locations, departments responsible for the treatment work and deadlines, the plan said.

By 2025, 90 percent of black and odorous water bodies in urban areas of all county-level cities should have been removed, it said. County-level cities in the Beijing-Tianjin-Hebei province region and the Yangtze River and Pearl River deltas, however, should fulfill the task one year earlier.

The guideline was issued on Thursday by four central government bodies, including the Ministry of Ecology and Environment, and the National Development and Reform Commission.

"Provincial-level governments should split treatment tasks, specify the duties of different departments and draft progress schedules for them," it said, adding that the progress of treatment in each region should be made public every six months.

The document came as China has essentially addressed black and odorous water bodies in the urban areas of prefecture-level cities and above. According to the ministry, over 98 percent of the heavily polluted water bodies in these major cities had been treated as of the end of 2020.

The document vowed to beef up financial support for waste water treatment to facilitate county-level cities in completing their tasks.

Aside from government investment, the country will introduce preferential policies to attract the participation of private capital in treating heavily polluted water bodies and renovating the sewage pipe network, it said. Financial institutions will be encouraged to offer more loans to projects for black and odorous water body treatment.

The document also includes measures to address the cost concerns of sewage treatment plants. Local governments are recommended to pay plants based on the concentration of pollutants in the sewage and the amount of sludge they have to dispose of.

The action plan stressed a lifelong liability accounting system for malpractices in the treatment work, saying leading officials who "shirk responsibility and fail to accomplish treatment tasks" will be strictly held accountable.

China has made continuous progress in water pollution control in recent years. Last year, the proportion of surface water that was classified as "fairly good" quality across the country reached 84.9 percent, up by 1.9 percentage points from 2020, according to the Ministry of Ecology and Environment.

In China, water quality is considered "fairly good" if it is at or above Grade III, the third-best level in the country's five-tier quality system for surface water.

Only 1.2 percent of the country's surface water was below the worst quality of Grade V in 2021, compared with 1.8 percent a year earlier.