A tank choking to death

Pollution

The once pristine Byramangala tank near Bidadi has now been reduced to a cesspool, thanks to reckless discharge of effluents into River Vrishabhavati, writes Ganadhalu Srikanta

Unbridled industrialisation has choked a water body to death on the outskirts of Bangalore city. The once pristine Byramangala tank near Bidadi has now been reduced to a cesspool, thanks to reckless discharge of effluents into River Vrishabhavati.

Byramangala tank is located in the course of the river Vrishabhavati. The water was pure and safe in the 1940s, when a dam was constructed for Vrishabhavati near Byramanagala, about eight kilometers from Bidadi on Bangalore-Mysore road. The tank once supported irrigation across 4,220 acres. It was also the source of potable water, and a lifeline for villages in the vicinity.

The course of Vrishabhavati began to shrink with the rapid expansion of Bangalore. While urbanisation swallowed swathes of the river basin, the deterioration of river water worsened with the discharge of effluents into the river during 1970-80.

Bidadi industrial area only further hastened the process. Consequently, not only River Vrishabhavati, but all the water bodies in its course were highly polluted. The river has been transformed into a raja kaluve (stormwater drain) for untreated industrial effluents. Water sources at Kengeri, Hemmigepura, Shylamangala and Sheshagiri villages all on the basin of this river have been extremely contaminated, making life difficult for the residents.

Contaminated groundwater
Groundwater in the Byramangala tank region is contaminated and borewells too yield brackish water. The setting up of an effluent treatment plant at Kengeri three years ago has been of no use. “We used the water for farming when it was dumped with organic and agricultural waste. Contractors of our nurseries insisted that we use this water as it yielded big-sized sapota (chikoo fruits). But the water turned toxic with the discharge of industrial effluents. The acid content in the tank water has gone up. It can even melt iron,” said Shivalingaiah, in charge of plantations, Horticulture Department.

An analysis of the water sample has revealed increased nitrate content in the water. The decay in water quality has adversely affected farming. Ninety per cent of paddy farming has come to a halt in a majority of the villages. The extent of arable land has shrunk to 600 hectares from 4,000 hectares. The quality of soil has deteriorated on account of the effluent discharge. The silk cocoons from Byramanagala do not fetch remunerative prices in the market.

A team of three scientists of University of Agricultural Sciences conducted a study on the socio-environmental effects of contaminated groundwater in Ittamadu, Ramanahalli and Gopahalli, six years ago. The findings revealed that the farm land in these villages (cumulative) had reduced to 259 acres from 318 acres.

The fertility of the soil had taken a beating because of the presence of heavy metals. Farmers have sustained a loss of Rs. 17,000 per acre of land, with 20 pc decline in paddy yield and 37 pc decrease in sugar cane yield. An analysis of the tank water and the vegetables grown using the tank water has thrown up worrying facts.

A study conducted by a team of Department of Environmental Sciences, Bangalore University, led by Nandini has revealed presence of  polyaromatic hydrocarbons, organocholrine, polychlorinated nitrate-M and other carcinogenic residues in the water.

Fisheries too has suffered due to the contamination of Byramangala tank water. While the tank used to support at least five species of fishes, it now sustains only one species, says H S Chandrashekhar, senior assistant director of Fisheries Department. Apart from eating into the livelihood of farmers, the contamination has also heralded new diseases in the villages here. Skin allergies have become common in farmers who work in the fields. However, there have been no studies in this regard. Medical store owners in and around Bidadi say that majority of the villagers purchase medicines for asthma and skin diseases. Mosquito menace has also become unbearable.

Dairy farming unaffected
However, dairy farming seems to have been least affected by the death of the Byramanagala tank. Para grass grows abundantly in the polluted water and the cattle feed on them. Such cattle have been yielding high quantity of milk. Farmers who sustained loss in agriculture have found solace in dairy farming.

There have been no empirical studies to substantiate the ill-effects of contaminated water on dairy farming. “What is the need for tests when things are smooth? Any report on the presence of hazardous elements may affect thousands of families depending on dairy farming,” a veterinary doctor said.

The choking of the tank, no doubt has left the village community devastated. However, the government is yet to initiate remedial measures. The only achievement so far is the setting up of an effluent treatment plant near Kengeri. Restoration of the tank to its pristine form should top the agenda.