Water Quality of Paldang Reservoir Became Worse

The water qualities of the major tap water sources, the Paldang Reservoir and the Nakdong River, became worse because of a drought.

The Ministry of Environment announced yesterday that the biochemical oxygen demand (BOD) of the Paldang Reservoir, the main source of tap water for the Metropolitan area, in January recorded 1.1 ppm compare to 0.9 ppm in January 2001. It is higher than the standard for the 1st grade water (1.0 ppm).

The water qualities of the lower reaches of the Paldang Reservoir, Amsa, Jamsil, and Noryangjin, became worse than those of last year because the discharged amount of water was dramatically reduced due to a winter drought.

In case of the Nakdong River, although Andong area, upper stream, maintained the 1st grade quality, the BODs of Goryung and Gupo areas, middle and lower streams, recorded 3.2 ppm and 4.7 ppm, which are worse than last year`s records of 3.0 ppm and 2.4 ppm.

Especially, the water quality of the lower stream of the Nakdong River, including Gupo, became the 3rd grade because the self-purification power of the river went down by the decrease of discharges of water from the four dams, including Andong Dam, up to 40 percent.

On the other hand, the BOD of the Daechung Reservoir in the Kum River improved to 1.0 ppm from last year`s 1.2 ppm. The BOD of the Juam Reservoir in the Youngsan River remained same as last year (0.7 ppm).

shchung@donga.com