Coastal and estuarine ecosystems are heavily influenced by the human species through pollution and habitat loss. Coastal pollution and its impacts have resulted in a number of environmental issues including the enrichment of enclosed waters with organic matter, pollution by chemicals such as oil, and sedimentation due to land-based activities.

India is blessed with a long coastline of about 7500 kilometers with over 1200 islands in the Exclusive Economic Zone (EEZ) of India, endowed with a number of estuaries, mangroves, coral lagoons, and mudflats.

However, increasing levels of organic and inorganic pollution in the coastal water over the years is posing a grave danger to the Dissolved Oxygen (DO) and microbial concentration levels which are the two most important indicators of the health of coastal waters.

Coastal Pollution can be attributed to untreated waste from domestic and industrial by bacteria leading to usage of enormous oxygen from the seawater ultimately reducing the dissolved oxygen levels in the sea and affecting the aquatic organism.

One should know that the recommended level of Dissolved Oxygen (DO) for ecologically sensitive coastal areas and beach tourism is 5 milligram per liter or above.

The ministry of Earth Sciences reported in December last year that DO levels observed to be very low at a few locations where raw sewage was being directly released into the sea adversely impacting mortality of larvae and juveniles who are quite sensitive to oxygen levels and also contributing to coastal pollution

Some of the major sources of coastal pollution in coastal areas identified by the ministry in include

• Municipal sewage
• Industrial effluent
• Aquaculture effluent
• Fertilizer used in agriculture
• Ports and Harbours
• Shipbuilding and ship breaking yard
• Fish processing industries/salt pans
• Tourists resorts/beaches
• Solid waste dumping

There are 13 states and union territories along the coastline of India which generates about 33215 MLD of sewage in total whereas sewage treatment capacity has been developed for only 12673 MLD!

Therefore, there is a huge gap of about 20542 MLD of sewage treatment capacity in the coastal areas. Thus, coastal pollution is on the rise with a huge gap in treatment.

A major portion of untreated sewage enters coastal waters through rivers, creeks, and rivulets that all are all interconnected.

In 2015, Central Pollution Control Board (CPCB) identified 302 polluted river stretches in the country. CPCB along with various state pollution boards have been monitoring river water quality since 1977-78.

Under National Water Quality Monitoring Programme (NWMP), 445 rivers are being monitored at 1275 locations and organic pollution has been identified as the predominant cause of water pollution that eventually increases the BOD levels.

Summary of Polluted river stretches in coastal areas (source: MoEF & CC)