BEIJING -- China has made progress in the comprehensive treatment of pollution in the Bohai Sea via strengthened supervision and steady reform, an official said Tuesday.

By the end of September, the number of unqualified fifth-class water quality sites in the Bohai Sea coastal waters was down to two from 10 in June, Huo Chuanlin, an official of the Ministry of Ecology and Environment, told a press conference.

Thirteen coastal cities and districts along the Bohai Sea have begun detecting and handling sources of pollution at each of the estuaries, in line with a work plan released by the ministry in February.

Prevention of environmental risks is strengthened as provinces and cities along the Bohai Sea defused 1,900 cases of potential hazards and registered emergency response plans for more than 5,400 companies.

China released an action plan in December on the comprehensive treatment of pollution in the Bohai Sea, setting the goal for the proportion of first-class and second-class water quality sites in the Bohai Sea coastal waters at around 73 percent by 2020.

The government earmarked more than 7 billion yuan (about $1 billion) in pollution treatment in the Bohai Sea in 2019.