River Tapi stinks because of release of untreated sewage water into it by many government and other offices. Surat Municipal Corporation (SMC) had found BharatSancharNigam Limited (BSNL), income tax department, government circuit house and police among those responsible for releasing sewage waters directly into Tapi. Of the 6,411 locations inspected by SMC, at least 1,543 illegal sewage drainage connections were found connected to storm water drainage which pollutes Tapi. Of the 1,543 illegal connections, 190 are of government offices, senior SMC officials told TOI. These details came to light during a study done by SMC in 2012. The survey cost SMC Rs 33 lakh, but the civic body is yet to stop the sewage flow into the river. This has affected the quality of water. The dissolved oxygen is reported 'zero' in Tapi near Ginger Hotel, Sardar Bridge and Ved Road. The biochemical oxygen demand (BOD) level is 315 milligram per litre as against the standard limit of 30 mg per litre. The chemical oxygen demand (COD) level is high in Tapi at Sardar Bridge, Vivekanand Bridge and Singapore areas. It is between 520mg/lt to 800 mg/lt when it should be below 250 mg/lt. "We are working to block the sewage connections to the storm water drainage. We will seal all the illegal connections," deputy engineer and in charge head of drainage department D C Bhagvagar said. When contacted, the income-tax department spokesperson said, "The office is not aware about this. We will have to check it at our end." About Umra police station's sewage connection to storm water drainage, a senior police official said, "I don't have the exact idea about it since it was constructed seven years ago." Offices found releasing sewage into storm water drainage: Bharat Sanchar Nigam Limited (BSNL), Ghod Dod Road Income tax department, Majura Gate S and S S Ghandhy Engineering College, Majura Gate Umra police station, Athwa Lines, Railway Reservation Centre, Athwa Gate State Government Circuit House, Athwa Lines Navsari Agricultural University, Ghod Dod Road SMC's pay and use public toilet, Gotalawadi, Athwa Gate, Ved Road State Bank Of India, Roopam Cinema Zonewise details of illegal sewage line connections found in storm water drainage Zones Govt Off Residential commercial Others Total North Zone 26 39111619552 East Zone4223811011401 West Zone273910884 South West Zone2461276118 Central Zone124510067 South Zone2165211108 South East Zone17124101152 Vesu Zone6151931 New East Zone15120330 Total190990305581543