Overview

Currently, there are 1,837 water quality monitoring stations in operation throughout the nation; 559 for rivers, 165 for lakes and marshes, 563 for reservoirs, 417 for agricultural area, and 133 for other regions. Monitoring categories include 26 items for river, and 30 for lakes and marshes. Especially, there are 40 automatic operating monitoring stations. The water quality is being monitored by measuring 5 common items such as DO, TOC, pH and other 9 optional items including VOC.

Underground water monitoring stations were used to evaluate water quality by measuring 15 items at 1,993 stations throughout the nation twice a year. BOD, one of major indicator for water quality standards, has improved continuously from 12.8% in 1991 to 13.8% in 1995, and 31.8% in 1998 and 42.3% in 2005.

River Water

Korea slightly revised its Green Vision 21 river quality targets during the review period (the share of rivers assigned Class I and II was reduced from 95 to 87%), but these nevertheless remain very ambitious: out of 194 watersheds (rivers and streams located in the four major basins of the Han, Nakdong, Geum and Yeongsan), Korea has assigned a Class I (i.e. best) quality objective to 120 catchments and a Class II objective to a further 49 catchments. Of the 40 graded lakes/reservoirs, 33 have been assigned a Class I objective, 3 a Class II objective and 4 a Class III objective. The grading system takes biochemical oxygen demand (BOD) as its key variable, but also considers variables such as pH, suspended solids, dissolved oxygen, total phosphorus and nitrogen, and total e.coli count.

As for the achievement of these targets, the country's surface water quality has unmistakably improved during the review period, even if the eight droughts suffered in various parts of the country since 1993 account for significant year-to-year fluctuations in quality. Still, the distance-to-target remains considerable: overall, fewer than one-third of classified rivers and streams met the quality objective in 2004. Almost half of the watersheds in the Han basin did not meet their targets, and this also was the case in two-thirds of the catchments in the Nakdong and Geum basins and five-sixth of the watersheds in the Yeongsan. A noteworthy weakness remains the lack of attention paid so far to the role of rivers as aquatic habitat: no biological water standards have been adopted and water managers appear to have little awareness of aquatic species.

The challenge is almost as great for Korea’s lakes, which are mostly artificial reservoirs supplying domestic, industrial and irrigation uses. One positive development is that the important 2005 water quality targets in the four major drinking water supply sources (Paldang, Mulguem, Daechong and Juam reservoirs) were met over the past three years; in the Paldang Reservoir, which is the main water source for the Seoul metropolitan area, some delicate fish and water insects, such as silver fish and planaria that live only in clean water, are being detected. Elsewhere, however, only 3 of the 33 Class I lakes and 1 out of 3 Class II lakes met the standard in 2004. Eutrophication is also a problem: 6 of the 40 graded lakes are classed as eutrophic (rich in nutrients), 19 are mesotrophic (with medium levels of nutrients) and 15 are almost mesotrophic.

Drinking Water Sources

The challenge is almost as great for Korea's lakes, which are mostly artificial reservoirs supplying domestic, industrial and irrigation uses. One positive development is that the important 2005 water quality targets in the four major drinking water supply sources (Paldang, Mulguem, Daechong and Juam reservoirs) were met over the past three years; in the Paldang Reservoir, which is the main water source for the Seoul metropolitan area, some delicate fish and water insects, such as silver fish and planaria that live only in clean water, are being detected. Elsewhere, however, only 3 of the 33 Class I lakes and 1 out of 3 Class II lakes met the standard in 2004. Eutrophication is also a problem: 6 of the 40 graded lakes are classed as eutrophic (rich in nutrients), 19 are mesotrophic (with medium levels of nutrients) and 15 are almost mesotrophic.

Rate of achievement of surface water quality objectives (%)

Water quality trends in four major drinking water reservoirs, 1997-2004 (mg/L)

Groundwater

Groundwater represents about 10% of overall abstractions in Korea and 30% of the estimated sustainable yield. The quality of groundwater is better than that of surface waters, even if on average 13% of shallow and 6% of deep aquifer observation wells show below-standard quality (groundwater quality is classified in three grades, depending on whether it is used for domestic, agricultural/fishery or industrial purposes). Abandoned boreholes pose a significant threat of contamination to groundwater: more than 43,000 such boreholes were capped and made safe during the review period. A nationwide search for further abandoned wells continues.

Coastal water

Coastal water quality is also categorised in three classes. About 35% of the coast meets the highest standard, for Class I. About 55% is in Class II and the remaining 10% is in the lowest grade, Class III. “Red tides” of decomposing algae, resulting from nutrient pollution from agricultural and other sources, are also occurring in some coastal waters and impose a considerable economic cost on fisheries and aquaculture. The Ministry of Maritime Affairs and Fisheries has formulated the National Marine Environment Preservation Plan to restore and maintain coastal water quality. Five severely affected areas, including Masan-Chinhae Bay on the south coast and the Incheon-Sihwa area near Seoul, were designated “Specially Managed Seas” under the Marine Pollution Prevention Act in 2000. Four other areas were designated “Environment Preservation Seas” the same year, to preserve their pristine environment.