Initiating a deep dive into a significant environmental issue of the country, it is essential to highlight the rampant coal mining activities in Nagaland that threaten the health of Assam’s Bhogdoi River. In 2019, the Ministry of Environment, Forest and Climate Change recognised Bhogdoi as one of the most contaminated rivers in Assam, ranking it 351st among the polluted rivers nationwide.
About River Bhogdoi
Having its roots in Mokokchung in Nagaland, the River Bhogdoi is also referred to as Tsujenyong nullah in the local dialect. This south bank tributary merges with the Dhansiri river near its confluence with the great Brahmaputra, and thus, it is an interstate river flowing between Assam and Nagaland.
Coal Mining in Nagaland: A Threat to Bhogdoi
One primary concern for the River Bhogdoi is the introduction of high manganese levels due to excessive coal mining activities in Nagaland. Apart from this, chemical waste from the numerous tea estates in the region is also polluting the river, making it toxic.
Other Pollutants Endangering the River
Another major challenge faced by Bhogdoi is the drains carrying both industrial and residential waste into the river, exacerbating the pollution and reducing its carrying capacity owing to heavy siltation. Furthermore, the burgeoning encroachments along the river bank have led to an increase in filth, garbage, and even human excreta. The practice of cremating bodies along the river bank also contributes to soil and water contamination in the region heightening the risk of water-borne diseases.
About River Brahmaputra
River Bhogdoi eventually merges into the Brahmaputra River, which originates under the name Siang or Dihang, from the Chemayungdung glacier near the Mansarovar lake in Tibet. This mighty river enters India west of the Sadiya town in Arunachal Pradesh and has several tributaries including Dihing River, Dibang River, Lohit River, Dhansiri River, Kolong River, Kameng River, Manas River, Beki River, Raidak River, Jaldhaka River, Teesta River, and Subansiri River.
Understanding Biochemical Oxygen Demand (BOD)
Water pollution due to organic waste is measured using a parameter known as BOD. It signifies the amount of dissolved oxygen needed by bacteria to decompose the organic wastes present in water, expressed in milligrams of oxygen per litre of water. The high BOD in Bhogdoi suggests low water quality and less oxygen for aquatic life. However, as BOD only considers biodegradable materials, it may not provide an all-inclusive measure of water pollution.
The Role of Chemical Oxygen Demand (COD)
Apart from BOD, COD is another critical parameter used to gauge pollution levels in water bodies. It measures the amount of oxygen required to oxidise both organic (biodegradable and non-biodegradable) and oxidizable inorganic compounds present in the water sample. This measurement helps to offer a more comprehensive understanding of the contamination levels.
In conclusion, while the River Bhogdoi confronts severe pollution challenges, it’s essential that appropriate measures are undertaken to mitigate the issue and protect this critical freshwater resource.
