Water pollution in the Cuejdi River is caused by waste deposits in rural areas and untreated sewage in urban areas. Tests on water quality were done by analyzing 30 samples taken in 2012. Results showed differences between rural and urban areas, with human activities impacting water quality in both. In urban areas, improper connections to rainwater systems degrade water quality, while in rural areas, waste dumped in the riverbed changes the water's chemical composition. The study also looked at data from 2000 to 2010, showing a decline in water quality over time.