Spot the river: Subernarekha in Mango chokes on jal kumbhi on Tuesday. Picture by Bhola Prasad
Subernarekha, the golden lifeline of Singhbhum, is under threat once again.
After a hiatus of two years, water hyacinths are back with a vengeance and have already smothered a 3km stretch of the river between Kapali and Bhuiyandih.
Environmentalist K.K. Sharma expressed serious concern over the mushrooming of these free-floating aquatic plants, known as jal kumbhi in local parlance. “Such dense cover of hyacinths is an indication of the rising pollution level in the river. The plant is multiplying fast on the surface because the flow of the river has weakened, which happens when the water is polluted,” the green crusader explained.
Also the head of zoology at Jamshedpur Co-operative College, Sharma underscored that jal kumbhi was detrimental to fish health and that of other aquatic life because it causes depletion of dissolved oxygen and makes water turbid.
Statistics show one hectare of hyacinths can deplete the same amount of oxygen as sewage created by 80 people. Two such plants take only 120 days to take its population to 1,100.
The last time hyacinths had smothered the flow of both Subernarekha and Kharkai was in 2011. The rivers had become watery graves for several varieties of fish, including rohu and katla. Hyacinths not just kill fish, they threaten human life too by helping in vector breeding.
Sharma sounded the alarm bell. “If their unbridled growth is not checked now, the jal kumbhi will help mosquitoes thrive and trigger diseases like malaria and chikungunya,” he said.
The environmentalist’s fears are not unwarranted. Health statistics show a spurt in malaria, chikungunya and dengue cases in 2011, when hyacinths had encroached upon the rivers from January till June.
Sources said regular streaming of domestic, industrial and agricultural waste into the river was the root of the problem. Director of Institute of Environmental Management and Studies (IEMS) N.K. Nag agreed and pointed out that that these plants thrive in nutrient-rich water. “Stagnation caused by effluents is largely responsible for growth of water hyacinths. If not cleared now, the very existence of the river will be at stake,” he stressed.
Officials at Jharkhand State Pollution Control Board (JSPCB) suggested that water from the Chandil reservoir and the check dam at Mango should be released into the Subernarekha at regular intervals to prevent stagnation.
“If the water is released, it will also check proliferation of hyacinths,” an official at pollution control board’s regional office said, adding that things would become normal with the advent of monsoon.
Braj Mohan Kumar, chief engineer of the water resources department posted at Chandil dam, said they released water to the river as a routine. “But a dry April has curtailed supply. We need a good spell of rain to wash away the hyacinths.” The reservoir is currently releasing 16.5 cubic metres of water to Subernareka instead of 20 cubic metres.
On why the JSPCB wasn’t taking steps to curb effluent flow to the river, regional officer R.N. Chaudhury maintained that they had collected samples for DO (dissolved oxygen) test. “The report will allow us to nail the causes of pollution and the perpetrators,” he said.