A survey conducted last year has shown that water quality in Lake Paldang, which is a source of drinking water for the 23 million residents of the Seoul metropolitan region, has significantly deteriorated. The survey of river water quality was done by the Environment Ministry, and found that average water quality at Paldang Dam was 4.0 ppm of chemical oxygen demand (COD), the worst since the government began tallying data in 1994. The biological oxygen demand (BOD) level came in at 1.1 ppm in 2005 and 1.3 ppm in 2008 and last year. The BOD also remained at 1b grade, indicating deteriorating water quality.
The situation is even worse at the Han River, which is not a source of drinking water. The COD level at the Gayang and Haengju bridges exceeded 7 ppm (grade 4), which makes the water impossible to use for agriculture, let alone for cleaning. Another ominous sign was the growth of the colon bacillus count. The count was collected at 11 points from Lake Paldang to Haengju Bridge and registered 38,466 per 100 milliliters, 4.2 times that of 2000 (9,277). Under existing water quality standards, water is classified as non-graded when the colon bacillus count exceeds 5,000 per 100 milliliters. Water at nine of the 11 sites, excluding Lake Paldang and Gwangjin Bridge, saw pollution rise.
The Environment Ministry has blamed severe drought resulting from climate change for the deteriorating water quality, but pointing the finger at nature is negligence. Korea suffered from drought last year, but summer saw above average precipitation. The government has spent more than 20 trillion won (17 billion U.S. dollars) to improve water quality at the Han River, including at Lake Paldang, but things have grown worse. This suggests Korea needs a more fundamental solution. Deteriorating water quality may be somewhat inevitable, given the heavy concentration of population in the Seoul metropolitan region. But accurate reasons must be discovered and presented as to why the COD level and the colon bacillus count increased so significantly, and why their levels widely vary by the area.
The Environment Ministry says the source water deteriorated but water is purified and cleaned well enough before being supplied to household taps, brushing off fears over tap water safety. To clean polluted source water, which contains high levels of colon bacillus, however, a massive volume of chlorine is needed for processing. This will increase fears over byproducts created in the disinfection process, including cancer-causing residual chlorine. It is impossible to produce quality tap water with a polluted water source.
Korea must reduce its level of agricultural chemical use, which is 10 times the average of member countries of the Organization for Economic Cooperation and Development, and toughen pollution management at commercial facilities, including restaurants and hotels, around the water reservoir. Also needed is advancing the timing of reinforced COD levels for sewage and waste water treatment facilities set to take effect in late 2012 within the given budget.