Delhi's Yamuna River experienced a worsening of pollution in November and December 2025, with faecal coliform levels rising significantly compared to October, according to DPCC data. Despite this increase, pollution levels remained substantially lower than in the same period of the previous year. Experts questioned the reported decline, citing typically low river flow during these months. Biological Oxygen Demand (BOD) levels were elevated, exceeding safe limits, while Dissolved Oxygen (DO) levels dropped, sometimes to zero at certain locations.