Context: Recently, the Gujarat government has awarded the contract for the Bhadbhut project in Bharuch.

• The Inland Waterway Authority of India has given clearance for this project.
• The project has faced protests from local fishermen because it is likely to impact fishing patterns, mainly those of hilsa (Tenualosa ilisha).

Bhadbhut project

• It is planned to be a 1.7-km causeway-cum-weir barrage across river Narmada.
• It is constructed at a place 25 km from mouth of the river, where it flows into the Gulf of Khambhat (Cambay).
• The barrage will stop most of excess water flowing out of Sardar Sarovar Dam from reaching the sea.
• It will thus create a sweet water lake of 600 mcm (million cubic metres) on the river.
• It also aims to prevent flooding in years when rainfall is higher than normal.
• The project has faced protests from local fishermen for its likely impact on fishing patterns, notably of hilsa fish.

Need of the project

• The main purpose of project is to prevent salinity ingress (the process of salt water invading areas which previously contained only fresh water).
• An estimated 16.30 million acre feet (MAF) of water used to be released from the Sardar Sarovar dam.
• By 2017, when height of the dam rose, flow into the Narmada river reduced to 4.7 MAF.
• Due to reduced flow of fresh water, saline seawater gushes into Narmada estuary during high tide, thus increasing salinity along the banks.
• The project is part of larger Kalpasar Project (which entails construction of a 30-km dam across Gulf of Khambhat between Bharuch and Bhavnagar districts, meant to tap waters of the Narmada, Mahisagar and Sabarmati.)

Why are fishermen upset?

• The barrage is expected to interfere with the migration and breeding cycle of hilsa.
• Hilsa is a marine fish that migrates upstream and arrives in the brackish water of Narmada estuary near Bharuch for spawning usually during monsoon (July and August) and continue doing so till November.
• Once the barrage is built, it is expected to block their natural entry.
• The fish production from Narmada estuary has fallen from 15,889 tonnes in 2006-07 to just 1,618 tonnes in 2014-15.
• The reduced outflow of water from the dam, industrial effluents flowing into the river and salinity ingress are believed to be the major causes of this decline.
• Part of Aliya Bet, and island in delta of Narmada, known for shrimp farming, is likely to get submerged due to the accumulation of water in Bhadbhut reservoir.

Narmada River

• It is a major river in peninsular India which flows in east-west direction, along with two other rivers Tapti and Mahi.
• The Narmada or Reva originates in the Amarkantak hills in Madhya Pradesh.
• It is the fifth largest river in the country, largest west flowing river and largest river in Gujarat.
• It flows towards the west in a rift valley between Satpura range in the South and the Vindhyan range in the North formed due to faulting.
• It is known as life Line of Gujarat and Madhya Pradesh.
• After flowing a distance of about 1,312 km, it meets Arabian sea south of Bharuch, Gujarat forming a broad 27 km long estuary.
• Four important tributaries: Hallon, Banjar, Tawa and Barna.
• This river traverses through Madhya Pradesh, Maharashtra and Gujarat.
• Narmada Bachao Andolan (NBA) is social movement spearheaded by native tribals, farmers, environmentalists and human rights activists against a number of large dam projects across river Narmada, particularly Sardar Sarovar Project.