The government said on the 25th it will cut total phosphorus (TP, the total amount of phosphorus compounds dissolved in water) discharges at major Nakdong River intake points with severe algal blooms and improve water quality to Han River levels by 2030. Total phosphorus is one of the main causes of algal blooms.
The Ministry of Climate, Energy and Environment and the Ministry of Agriculture, Food and Rural Affairs announced a Nakdong River water quality improvement plan the same day. Near the Mulgeum water intake plant in Yangsan, South Gyeongsang, a key Nakdong River water source, water quality averaged grade 3 by TOC (total organic carbon) and grade 2 by TP from 2020 to 2024 under legally mandated environmental assessment metrics. The Paldang Dam on the Han River is grade 1 by both TOC and TP.
In particular, 80% of the 781 nationwide algal bloom alert days over the past five years occurred on the Nakdong River. According to the National Institute of Environmental Research, as of 2023, 12,498 kilograms of total phosphorus were discharged into the Nakdong River per day. More than 80% of this was found to result from farmers using chemical fertilizers and livestock manure in excess of recommended amounts. Livestock manure or compost discharged from farms without treatment flows into the river, worsening algal blooms and stream pollution.
◇ Livestock manure, the "main culprit" of water quality deterioration, to be turned into fuel... guide appropriate fertilizer application
The government said it will reduce algal blooms and improve Nakdong River water quality to grade 1 by TOC and TP, the same level as the Han River today, by 2030. To do that, TOC must be 3 mg or less per liter, and TP must be 0.04 mg or less. Near the Mulgeum intake on the Nakdong River, the 2020–2024 annual average TOC is 4.1 mg per liter, and TP is 0.042 mg.
To this end, the plan is to cut total phosphorus discharges by 30% from 2023 levels. The government will guide farms to convert half of the compost and liquid fertilizer applications that exceed recommended amounts of livestock manure into solid fuel or biogas. Since 2024, the government has been pursuing a plan to dry and compress cattle dung from barns by mixing it with auxiliary materials such as sawdust and rice husks to use as fuel. The climate ministry will establish management standards for stockpiled compost (livestock manure fermented with microorganisms together with rice straw, etc., and piled outdoors by farms) and measures to sanction violations.
The government will also devise a plan to calculate the appropriate fertilizer amount for crops grown by farmers and build a system to check and manage whether the appropriate amount is being applied. In addition, it will promote the distribution of controlled-release fertilizers (coated so that nutrients are released slowly in line with the crop growth period), which can reduce use compared with general fertilizers.
Industrial wastewater flows into the Nakdong River at 470,000 tons per day, 60% of which comes from the Gumi and Daegu areas. The government will introduce advanced purification processes used in water treatment plants to major public sewage and wastewater treatment facilities that process 10,000 tons or more per day. Advanced purification processes are high-level treatment steps that remove trace contaminants such as per- and polyfluoroalkyl substances that are difficult to eliminate with conventional advanced treatment alone, which uses ozone and activated carbon.
Minister Kim Seong-hwan of the climate ministry said, "The measures were prepared with the aim of structurally reducing water pollution from the source," adding, "By pursuing the clean Nakdong River water supply project together with the seasonal algal bloom management system, we will secure a stable supply of safe drinking water for the public."