Pollution gets to groundwater

The photo on the left taken from Trimohani Bridge shows the jet-black waters of the Balu. Rampant dumping of sewage, industrial waste and garbage has turned the water into a thick liquid, right picture, which spread stench in the area. Environmentalists' and civil society's repeated demand to solve the problem produced little result and the Department of Environment seems to have given up hope as it does not measure the water's pollution level anymore.Photo: SK Enamul HaqPinaki Roy

River pollution around the capital has reached such a level that the groundwater system where the aquifers are recharged from the riverbeds is being contaminated, a recent study shows.

In the seven months from November to April, virtually no water but only stinky mucky liquid flows in the gradually narrowing rivers -- the Buriganga, Shitalakshya, Turag and Balu -- as no governments could stop discharge of liquid waste into them.

A recent study jointly done by the World Bank and the Institute of Water Modelling (IWM) says: "The groundwater system is being contaminated in areas where aquifers are recharged from the riverbeds. The pollution is creeping towards the central part of the city with time."

The study mentions groundwater in Hazaribagh, home of toxic tannery industries, as the most affected. "It is quite likely that in the long run groundwater would be affected from the surface at solid waste or industrial effluent dumping ground," the report adds.

Currently, 85 percent of the total demand of city water is met through groundwater sources as most of the surface water is contaminated, according to Dhaka Water and Sewerage Authority (Wasa).

The IWM survey shows there are over 300 various effluent discharge outlets in Dhaka city and Narayanganj. Of these, 19 outlets carry major discharge of mixed effluents of industrial and household waste which is falling into the rivers around the capital.

Movements by environmentalists as well as demands by the civil society could not change the situation. Now the situation is so worse that no living organism survives in the stinky thick black liquid of the Buriganga, Shitalakshya, Balu and Turag.

The foul odour of the polluted black water strikes the nostril even at half a kilometre distance. The pollution has become so 'usual' that the Department of Environment now does not measure its level anymore.

The overall situation suggests that the city dwellers have no immediate respite from it.

During a recent visit to the Buriganga, Shitalakshya, Balu and Turag rivers this correspondent could not stay for long on the banks.

At the Sadarghat and Mitford Hospital points many passengers were seen crossing the river on boats covering their nose.

"It stinks round the clock. We are habituated with this but are really having hard times due to the mosquitoes," boatman Bazlu Mia said.

At the Kanchpur Bridge point of the Shitalakshya, Trimohini point of the Balu and Tongi point of the Turag the waters are so stinky and polluted that hardy any fish or other aquatic life form could survive there.

People living by the rivers say just twenty years ago these rivers abounded with different varieties of fish.

"We used to see Gangetic dolphin in the Buriganga near Millbarrack point even in the end of the 80s," says Shakhawat Hossain, a resident in Shyampur.

But in just two decades indiscriminate discharge of human excreta, household garbage and industrial waste, mainly liquid waste of dyeing and tannery industries, left the rivers dead.

The Wasa treats the polluted black water of the Shitalakshya and Buriganga and supplies stinky water to the city dwellers by 'purifying' it with chlorine and ammonia sulphate.

Now the pollution has set in on the rivers Buriganga and Shitalakshya and made it almost impossible to treat their waters.

BUET RESEARCH ON RIVER POLLUTION

A recent research by Bangladesh University of Engineering and Technology (Buet) shows the pollution level in the Buriganga, Shitalakshya, Balu and most parts of the Turag so high that simply no living organism can survive in their waters.

A three-year research finds that some invertebrates and small organisms come to life in these rivers when water flow increases in the rains. But these life forms completely disappear in the dry season, the researchers add.

The researchers have found the Turag, Balu, Buriganga and Shitalakkhya to be the most affected rivers.

They say the waters in these rivers are affected by industrial effluents and wastewater. The waters are also affected by municipal sewage disposal contamination, agro-chemicals and large amount of suspended sediments carried by upstream flow.

The oxygen level of the Buriganga, Tongi canal of Turag and a part of Norai is less than one in per microgram. All species of local fish need 4-6 level of oxygen in per microgram to survive, says the study conducted by the Buet water resources department.

During water quality assessment using bio-indicators method, the researchers collected samples thrice from the Chadnighat point of the Buriganga but twice failed to get any life form.

Bio-indicators respond to the quality deterioration from multiple and varied pollution sources and thus provide an overall picture of water quality.

"In this method we collect sediments from the riverbed and test the environmental health of the river by counting available aquatic creatures in those. The creatures in the sediments vary on the basis of pollution level," says one of the researchers.

The researchers collected samples and tested those in pre-monsoon and post-monsoon seasons.

In the post-monsoon season oxygen level increases slightly but not enough, the researchers observe.

They found that oxygen levels were 0.7 and 0.25 in Chadnighat point, 0.27 and 0.63 in the Norai near Trimohini, and 0.27 and 0.63 in the Turag in Tongi before and after the monsoon respectively.