The Environment Ministry opened the Ipo Weir on the Han River on Thursday in an effort to revive the four major rivers that underwent refurbishment under the conservative Lee Myung-bak administration.

The Ipo Weir will release water to a level that does not affect the water supply to nearby farmlands, the Ministry of Environment said. The Ipo Weir is one of 16 weirs constructed as part of a project involving four major rivers in the country.

Nine weirs have already been partly or completely opened as of September, and the ministry aims to release the water in five more weirs by mid-October -- three on the Geum River and two in Yeongsan.

First proposed in 2009, the project aimed to revitalize the country’s four major rivers -- the Han, Nakdong, Geum and Yeongsan -- so that they would better withstand floods and droughts.

Environmentalists and the liberal faction opposed the project, questioning its effectiveness in the management of floods and droughts, and raised environmental concerns. The conservative administration pushed ahead with the project nevertheless, arguing that it would improve water quality, secure water resources and provide economic benefits to regions surrounding the rivers.

Construction began in 2009, and 16 weirs and dams were built on the four rivers over a two-year period. According to the most recent audit, conducted by former President Park Geun-hye, the project cost taxpayers some 31 trillion won ($27.4 billion), more than its initial planned budget of 22 trillion won.

The project, however, appeared to worsen water quality and increase algal bloom in the rivers every summer -- to the extent that the phenomenon was often dubbed “green algae latte.”

Amid public concerns over the water quality of the rivers and the reduction in water resources, President Moon Jae-in ordered an inspection and audit of the project, almost immediately after his inauguration on May 10, 2017.

The presidential office said at the time that the project had failed to maintain the right balance between safeguarding the environment and securing water resources.

Since June last year, the Environment Ministry has been monitoring, opening and closing the weirs and dams to observe environmental changes in 30 areas, including water quality and water ecology.

In a parliamentary interpellation session on Thursday, Environment Minister Kim Eun-kyung said she takes responsibility for the four rivers project.

“(The project) was conducted by the former government, but as the incumbent environment minister, I admit the Environment Ministry has not been doing its work properly,” she said.

Appointed by the Moon administration in June 2017, Minister Kim has been critical of the project, saying it has interfered with the “original functions” of rivers.

On June 29, the Environment Ministry reported the results of its yearlong monitoring, which showed improvement in the water quality. According to ministry data, the level of algal concentration in the Sejong Weir and the Gongju Weir -- which were fully opened -- dropped 40 percent, while water in other nearby weirs also cleared.

The ministry’s four rivers inspection team will be reorganized to focus around a water management committee that is expected to be launched next year. Based on data collected in past years, the new committee will come up with final measures for the weirs and dams, determining whether they should be abolished or not, the ministry said.

By Jo He-rim (herim@heraldcorp.com)