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The rampant coal mining in Nagaland, coupled with waste discharge from tea estates and encroachment have been sounding death knells for River Bhogdoi in Assam.
The river, one of the south bank tributaries of the mighty river Brahmaputra, originates from Mokokchung in Nagaland where it is also known as Tsujenyong nullah.
The total catchment area of the inter-state river (flowing between Assam and Nagaland) is 1,545 square kilometres and travels 160 kilometres before joining Dhansiri river near its confluence with Brahmaputra.
Manganese contamination
In 2019, the Union Ministry of Environment, Forest and Climate Change declared Bhogdoi as one of the most polluted rivers in Assam and 351st among the polluted rivers in the country.
In June this year, dead fish were sighted in several areas along the banks. These deaths were linked to contamination. Locals in Jorhat city and neighbouring Mariani complained of water turning sticky and murky.
Coal mining in Nagaland introduced high levels of manganese in the river, an investigation conducted by the Public Health and Engineering Department (PHED) of Jorhat division indicated.
The department also suggested decontaminating the water before supplying to towns and testing several times before supplying for consumption.
Kuldeep Das, executive engineer, Jorhat PHED, said:
We tested the water and found the presence of manganese in it. We didn’t do further testing. The coal mining in neighbouring Nagaland could be the reason for it but we cannot say conclusively. The water is, however, safe for drinking after purification and several hundreds of people depend on it.
The contaminated water raised serious health concerns among people in Mariani, around 18 kilometres from Jorhat, mostly inhabited by tea garden workers and dependent on Bhogdoi for drinking water.
Locals in Mariani had also complained of tea brewed from it tasting bitter. “We panicked after finding the water sticky and complained to the administration. The officials have assured us of looking into the matter,” said Raju Lepcha, 34, a tea garden worker.
Chemical waste from the tea gardens in Mariani is also believed to be turning the river poisonous and polluted.
Reduced carrying capacity
Tocklai, one of the major drains, as well as some other smaller drains carry municipal waste from Jorhat and into the river.
“The drains carry industrial and residential wastes. The river has also become heavily silted, reducing its carrying capacity. There have been no systematic studies done to save the river,” said Mirza Zulfiqur Rahman, environmental researcher who spent his childhood in Jorhat.
The biochemical oxygen demand (BOD) of Bhogdoi was four milligrams per litre (mg / l) in September 2018, up from 1.1 mg / l in 2016, according to the River Rejuvenation Committee (RRC) set up by the state government.
The high BOD indicates low water quality and less oxygen for aquatic life.
Unchecked encroachment
Jorhat city has urbanised rapidly due to its strategic location near Nagaland border that facilitates transit of goods. The work requires an increase in manpower.
The massive encroachments along the river bank have been not only making the river narrower but also increasing the filth and garbage.
Earlier, there were fewer houses along the bank but as people migrated from other states over the years, constructions increased, said Ramdev Yadav, 52, a migrant labour from Bihar. “The laxity of administration in keeping a check on encroachments helped people to encroach the river bank as much as possible.”
To make the situation worse, the local population use detergents for washing clothes and soaps for bathing in the river leading to the release of highly toxic chemicals of non-degradable variety into the water. This pollutes the water and threatens aquatic life, Mirza said, adding:
Disposing human excreta and cremating dead bodies along the river bank are gradually contaminating the soil and water of the region. This is increasing the threat of water-borne diseases.
Bhogdoi is now considered a drain, not a river, the expert said.