Sah was clearly hinting at the fact that the released fishes would not survive.
For healthy aquatic life in a river, minimum level of dissolved oxygen (DO) should be 5mg per liter. The fishes were destined to die, given the very low quality of water in Bagamti.
Water quality in Bagmati, particularly downstream Gokarna, is not good, and it further deteriorates when the sewage treatment plant at Guheswari gets interrupted by power outage.
The DO level in Bagmati´s water varies as per locations.
According to Anjita Rajbanshi, a lab officer at High Power Committee for Integrated Development of Bagmati Cilization who examined Bagmati water in January 2013, the DO level at Gokarna is 8.9 mg per liter and 6.7 mg per liter in Jorpati. At Pashupati Aryaghat, the DO level is slightly better at 7.4mg per liter.
But, in Tilganga and downstream, the DO level plummets to 0 mg per liter, a condition in which aquatic life, baring certain types of insects, does not exist at all.
Bagmati River did not fell to ruin overnight. The story of its decline runs parallel to the growth in the urban population.
Three decades ago, Bagmati River was home to various species of aquatic lives. At the time, the river´s water was good for all sorts of aquatic life, agriculture and even for bathing.
In 1980, researcher TK Shrestha had recorded 23 species of fish in his fish survey for a Tribhuvan University journal.
As the quality of water continued to degrade, significant numbers of fish species vanished down the years.
The fact was conformed by another fish survey conducted by the Bagmati Basin Water Management Strategy and Investment Program in 1994. The study recorded only 11 species of fishes in the river.
According to Dr Bandana Pradhan, who is a professor at the Department of Community Medicine and Public Health at the Institute of Medicine (IOM), only tolerant aquatic creatures can survive in the water below the minimum DO value. "There are only a few species that can survive in the polluted water," she says. "For fresh water fishes to survive, the water quality should be really good."
Generally, a river is assumed dead when DO value reaches 0 mg per liter of its water.
In the case of Bagmati River, the quality of headwaters at Sundarijal in the foothills of Shivapuri Mountain is still good. At locations such as Gokarna and Pashupati Aryaghat, the river is still alive, but its condition needs to be improved.
The river looks more like a cesspool as it flows down toward the city because all urban sewers are dumped into the river and its tributaries.
People, not government, can make the difference
Dr Bandana Pradhan
Professor, Department of Community Medicine and Public Health,
Institute of Medicine, Tribhuvan Univeristy
What is the level of dissolved oxygen (DO) value for aquatic life?
There should be 5 mg per liter of dissolved oxygen (DO) for a healthy aquatic life in a river. This is not to say that aquatic creatures cannot survive below this level. Very few tolerant species can survive in highly polluted waters.
What causes decrease in DO level?
The steady increase in population of Kathmandu and the direct discharge of domestic sewage into the Bagmati River and its tributaries has resulted in the high level of pollution. People also throw whatever is left after a ritual into the river. These organic wastes take oxygen in the process of decomposition, causing reduction of the DO level in the water.
Is there possibility of reviving aquatic life in Bagmati and how long will it take?
The standard renewal time for surface water (River water) is six months to two years. If people stop dumping wastes into the Bagmati River, it can revive in five years´ time. Along with the waste management, we must protect the source of the river and its tributaries, stop pumping out underground water from near the river, and the concerned authority must enforce the urban planning policy in the city.
What is the major obstacle against the revival program and what should the government do?
The major obstacle so far has been the lack of coordination among the government departments working for Bagmati conservation and revival. The other major factor has been inconsistencies in the projects often caused by the change in the working team with the change in the government. All the political parties must pledge that they would not let change in the government affect the Bagmati River project.
What role the people of Kathmandu can play to restore the Bagmati River?
Government, alone, cannot do much to restore aquatic life in the Bagmati River. People of Kathmandu can play a major role to make a difference. After all, it is the people who polluted the river knowing fully awareness of the consequences. The habit of dumping domestic wastes in the river has turned people blind to the damage it causes to environment. Regular and active participation can change this habit. I have seen many people taking part in Bagmati cleaning programs in the recent times.
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