VietNamNet Bridge – The Investigation Agency has said that Ms. Nguyen Thi Ngoc, 53, a votive money maker, created the "blood-red stream" in Dien Bien.
Dien Bien stream turns blood-red because of chemicals

Lieutenant Colonel Nguyen Huu Thai, Deputy Chief of Police of Dien Bien district, has said that the previous information about the "blood-red stream" in Thanh Hung commune, Dien Bien district was not completely true.
Immediately after being informed by locals, the police investigated the incident and identified that Ms. Ngoc was the one who created the blood-red stream. The police said Ngoc poured a bucket of red pigment into the Nam Khenh Stream, leading to rumors about the red colour among local residents.
Ngoc told the police that her family quit producing votive paper money two years ago. Recently they repaired a house and found a bucket of red pigment used to make votive paper money.
Builders carried the bucket to and poured the pigment into the stream of Nam Khenh.
Lieutenant Colonel Thai said some newspapers wrongly reported that fish died in the river. In fact the red pigment dyed a section of the stream, and there were no dead fish.
Xuan Ha