The researchers studied water quality in the upper stream of Mankyeong River to understand how to improve it. They looked at factors like water temperature, pH levels, oxygen content, and pollutants like nitrogen and phosphorus. They found that the water quality varied across different sites, with pollution being worse in the dry season. The area near Samyea Bridge had the highest pollution levels. Overall, the water quality often exceeded standards for agriculture, indicating a need for better control and management of the river's resources.