The evening walk around the tank is always a pleasant one. It is called Narsipura-2 in the way we have gone about giving names to our waterbodies. As with all the other waterbodies, this too was made by throwing an earthen bund across a valley to hold water for irrigation. Paddy would be cultivated in its command area and the tank would go dry for a good part of the year.
The original purpose of the tank has gone. There is no paddy but only houses in the command area. The city has worked at deepening it, created an island for the birds and planted trees on the bund all around for people to walk. Citizens have been an active participant in the whole development and continue to do so even now.
In one corner a stench is emanating. Sewage has accumulated and the smell is enough to make one gag. The residents nearby have a tough time. Where has the sewage come in from? It looks like it has flowed in through the storm-water drain where some amount of raw sewage always flows.
Some of the locals take a walk all the way upstream of the storm-water drain along with the corporator to find out where the sewage is coming in. Many spots are identified and the local water utility engineer promises action to fix this.
It is only through concerted citizen action with political support that tanks like Narsipura 2 can be maintained.
Improper use
In the meantime a borewell has been dug meant to water the trees planted alongside the lake, especially in summer. Now, however, the borewell is pumping water into the lake. Approximately 200,000 litres of potable water is being sent into the lake daily. Good enough to give 2,000 people or 500 households water at 100 litres per capita per day. Perhaps it is to dilute the sewage in the tank, perhaps it is to fill the tank. In any event the imagination of the tank as a perennial water body causes such action to be taken.
Whereas a tank should collect rainwater and recharge the aquifer here an aquifer is being depleted to fill a tank in a city starved for water. Our imaginations and our narrative drive our actions.
A tank now in urban Bengaluru is a recipient of nutrients from treated and untreated sewage. This causes the soil in the tank to stay in an anaerobic condition causing a particular type of vegetation to develop which is attuned to swamp- or marsh-like conditions.
Our tanks are now mostly wetlands. Wetlands have a particular vegetation and bio-diversity, do not need external water sources to support them, can handle a bit of raw sewage, and can flourish well with a larger biodiversity than a lake. Yet we try to remove ‘weeds’ as we call the wetland plants, fill them with water and in general spend ourselves silly.
The moment we realise that a tank is not a modern-day swimming pool and deal with it as a wetland will be the day when we will have done justice to them. The Karnataka Lake Conservation Development Authority has moved the Centre to declare 176 tanks in Bengaluru as wetlands. If this happens it will be the best thing for our tanks.
That would be water wisdom.
