The water quality in Mankyeong River was studied at 13 sites over 6 months in 1995 and 1997. Levels of certain pollutants peaked in different months, with some exceeding safe levels. The river water was not suitable for irrigation in most areas, except for a few sites. Pollution from city sewage and swine waste affected different parts of the river. The highest ionic concentrations were found at the Yocheon floodgate due to city and industry sewage. The river had high levels of certain ions, with chloride being the most abundant anion and sodium being the most abundant cation.