As the role of a physician, I think that the primary goal is how to best improve the health of both the people in the community as well as the health of a community at large. A large part of doing this is prevention of disease. As such, this is where I would focus my efforts a the leading physician of a medical action committee. To do this, I would make efforts to keep the people out of the river as much as possible while educating and promoting ways to reduce impact on pollution. Lofty goal granted, but necessary ones to at least attempt achieve. Of the many factors that need to be addressed, the ones I think should take precedence are the use of the river water for bathing (non-ritual), brushing teeth, drinking (without boiling properly), and using the restroom. The reasons for this are rather self explanatory in terms of preventing disease that may be carried in the water. To do this, an effort will likely need to be promoted by more than just the physician, so getting as many local leaders and governmental and international officials on board would be ideal. However, realistically speaking, it is likely that only one or two of the would be able to be coordinated effectively, so focusing on the WHO (which may be able to provide medical resources) and the priest (who likely holds great respect in the community) would be the place to start. Of the many things that need to be solved, I think that providing clean alternatives or preventing unhealthy use of the water is the most critical problem to tackle. This leads into what I think is the most obvious critical decision which is whether to ban the use of the river except for approved purposes (such as religious use). That being said, my response, at least initially, to the address the water issue in Varanasi would be to educate the population in the risks of the water in a way that they may understand and actually pay attention to (likely to be done with the help of a local priest or respected elder/leader).
Moving forward- Physician