Chongqing Nanchuan reported "an abnormal color in a section of the river": the abnormal water quality is caused by the outflow of cave water.

Today, the People's Government of Nanchuan District, Chongqing City issued a notification on the disposal of water quality anomalies in the Xiaohzihe Three River Corridor Bridge section of Nanchuan District. The details are as follows: Nanchuan District continues to carry out the disposal of water quality anomalies in the Xiaohzihe Three River Corridor Bridge section through its working group. After investigation, it was found that the direct cause of the water quality anomaly was the seepage from a cave 500 meters upstream of the Three River Corridor Bridge. According to the results of water quality monitoring of the seepage from the cave on November 11th, among the 13 detection items, 7 indicators including chemical oxygen demand, ammonia nitrogen, permanganate index, total phosphorus, manganese, sulfide, and anionic surfactants exceeded the Class III standard limits of surface water environmental quality, making it the direct source of pollution for this section of the river.