New Delhi: River Yamuna appears to have received some of the monsoon cleansing that was due in early July. In Aug, the river showed a substantial reduction in sewage contamination at some downstream stretches compared to July as well as the same time last year.Despite the improvement, though, organic pollution is still high, and a large stretch of the river is still not fit for bathing.A Delhi Pollution Control Committee (DPCC) sample, collected on Aug 5, shows that fecal coliform — an indicator of untreated sewage — fell sharply at several points downstream. At ITO Bridge, the level was 17,000 most probable numbers (MPN)/100 ml, compared with 54,000 a year earlier. At Okhla Barrage, it was 23,000 against 30,000 in Aug 2025. The figures at Nizamuddin Bridge were almost unchanged at 13,000 units, while Asgarpur recorded 36,000 against 35,000 last year. This goes against a desirable limit of 500 MPN/10 ml and a standard of 200 MPN/100 ml.The improvement is significant against the backdrop of the river’s condition in early July, when the absence of adequate monsoon flows had left pollution levels largely comparable to June. Additional routine monsoon flow began reaching Yamuna from July 9, providing the river with the increased volume needed to dilute and flush accumulated pollutants.The Aug data also shows some improvement in dissolved oxygen (DO), another measure of the river’s health. At ISBT Bridge, DO rose from 2 mg/l in Aug 2025 to 3 mg/l this year, while at Nizamuddin it increased from 4 mg/l to 4.6 mg/l and at Okhla from 3.2 mg/l to 4 mg/l. At Asgarpur, it rose marginally from 2.3 mg/l to 2.6 mg/l. However, these levels remain below 5 mg/l, which is the standard required for bathing.The reduction in fecal contamination downstream, therefore, suggests that higher monsoon flows have helped move and dilute some of the sewage load that had accumulated in the river during the lean-flow period. But it didn’t translate into uniform improvement in all pollution indicators.Biochemical oxygen demand (BOD), which depicts the capacity of water to clean itself, is the amount of oxygen required for the water to treat organic matter in it. The levels were higher at most downstream locations than last Aug. It rose from 24 to 28 mg/l at ISBT, 14 to 18 mg/l at ITO, 7.2 to 12 mg/l at Nizamuddin, 7 to 10 mg/l at Okhla and 11 to 16 mg/l at Asgarpur. At Palla, however, BOD improved from 3.7 to 3 mg/l.According to Bhim Singh Rawat of South Asia Network on Dams, Rivers and People (SANDRP), the timing of the sampling matters. He said the floods this season had been erratic and the river had not crossed even the warning level.He also pointed out that the maximum discharge the river received this year from the Hathnikund barrage was 63,109 cusecs on Aug 4, the day before the sampling.Since 2014, the river had breached warning levels each year, barring 2024, when it was 204.38 m, against the warning level of 204.50 m. This year, the maximum it reached was 204.09 m on Aug 8, which is the lowest since Aug 2004 (203.73 m) and July 2014 (204 m).Rawat also pointed to increased diversion into East and West UP canals at Hathnikund. During the 2023 Delhi floods, the diversion to the canals was stopped once upstream water influx breached 50,000 cusecs and all was released to the main river.“However, the threshold for when water must be released into the main river was raised from 60,000 cusecs to 70,000 cusecs and subsequently to 1 lakh cusecs from 2024. With flows crossing 60,000 cusecs only once or twice this season, he said, canal operations were not meaningfully curtailed, delaying the additional water that could have provided Yamuna a much-needed monsoon flush,” Rawat said.
