With World Environment Day being celebrated on Thursday, the Yamuna river today projects a grim picture of increasing pollution levels. "The Biochemical Oxygen Demand (BOD) load, an important indicator of pollution levels, has increased by 13 per cent over last year,' Central Pollution Control Board (CPCB) has said in its latest report. This rise might be because of increase in generation of BOD load in the city or decrease in treatment efficiency of sewage treatment plants (STPs). "The 22-km stretch which runs through the Capital contributes 77 per cent of the total pollution recorded from the 1768-km-long river,' the CPCB said. As many as 18 drains in the national Capital flowing into the Yamuna contributed to a total of 265 tonnes/day BOD load in 2007 while canals in Agra and Gurgaon added around 50 tonnes. Of these 18 drains, five drains