Goa, July 16 -- Despite the gov ernment investing crores of rupees in building sewerage infrastructure to prevent pollution of Goa's rivers, un treated sewage continues to flow through open drains in Margao and ultimately into the River Sal, raising un comfortable questions over whether the expensive net work is delivering the envi ronmental protection it was meant to provide. Social activist Sanjay Dessai said "It is shocking that, even after spending crores of rupees on sewage treatment infrastructure, raw sewage is still being discharged into nallahs and ultimately into the Riv er Sal. This is a complete failure of the system and raises serious questions about the functioning, maintenance and moni toring of the sewage treat ment networ...