The Farakka Barrage is a dam that diverts water from the Ganges into a canal near the town of Tildanga in Murshidabad District. The canal provides the Hooghly with water even in the dry season. It parallels the Ganges, past Dhulian, until just above Jahangirpur where the canal ends and the river takes its own course. Just south of Jahangirpur it leaves the Ganges area and flows south past Jiaganj Azimganj, Murshidabad, and Baharampur. South of Baharampur and north of Palashi it used to form the border between Bardhaman District and Nadia District, but while the border has remained the same the river is now often east or west of its former bed. The river then flows south past Katwa, Navadwip and Kalna. At Kalna it originally formed the border between Nadia District and Hooghly District, and then further south between Hooghly District and North 24 Parganas District. It flows past Halisahar, Chunchura, Rishra, and Kamarhati. Then just before entering the twin cities of Kolkata (Calcutta) and Howrah, it turns to the southwest. At Nurpur it enters an old channel of the Ganges and turns south to empty into the Bay of Bengal. Two of its well known tributaries are Damodar and Rupnarayan.
The nexus formed by the Hooghly River (Ganga) and the Bay of Bengal, called Ganga Sagar. This is a sacred place for Hindus. A dip in the ocean, where the river drains into the sea is considered to be of great religious significance particularly on the Makara Sankranti day when the sun makes a transition to Capricorn from Sagittarius and this place becomes home to vast fairs, drawing visitors and recluses from all over the state.
The river was an important transportation channel in the early history of Bengal, and later with the colonial trading ports. The river's presence is one of the reasons chosen by the British to settle there at Calcutta. The Dutch/French colony at Chandannagar on the Hooghly was once the rival of British Calcutta, but was eclipsed by Calcutta in the colonial wars of the 18th century. The river banks hosted several battles and skirmishes towards the start of the colonial era, including the Battle of Plassey Palashi, as well as earlier wars against Maratha raiders. On eastern bank lie many historic and wealthy towns like Murshidabad, Jangipur and Ziaganj.
In 1974 the Farakka Barrage began diverting water into the Hooghly during the dry season so as to reduce the silting difficulties at Kolkata's port.
Like the rest of the Ganges, the Bhāgirathi-Hooghly is considered sacred to Hindus, and its water is considered holy.
The Bhāgirathi-Hooghly river system is an essential lifeline for the people of West Bengal. It is through this river that the East India company sailed in to Bengal and established their trade settlement - Calcutta, which later grew up to be one of the greatest cities of the world and capital of the erstwhile British India. People from other countries like French, Dutch, Portuguese, etc all had their trade settlement by the banks of this river.
The river provides perennial supply of water to the plain of West Bengal for irrigation and human & industry consumption. The river is navigable and the major transport system in the region with a huge traffic flow. For a long time, the Calcutta Port was the biggest port of India. Though in the past its significance had gone down, but recently it had again came up to the 3rd position in the list of Indian Ports. The fish from the river are important to the local economy.
The modern container port of Haldia, on the intersection of lower Hooghly and Haldi River, now carries much of the region's maritime trade. One new port will be built in the deep sea to reduce load on Calcutta port.
Hooghly river valley was the most important industrial area of erstwhile state of Bengal. Due to declining jute industry, the prime industry of this region, it lost its glory and partitioning of Bengal. But still it is one of the biggest industrial areas of India. Except Kolkata and Howrah it has number of small cities which forms the Greater Kolkata Agglomeration, the second biggest Indian city and former capital.