The watery tract next to Purbasha Housing Estate. A Telegraph picture

The controversy over the nature of an 11-bigha plot — ‘tank’ or ‘land’ — has thrown up a number of questions the civic body is struggling to answer.

If the arbitrary tank list that the civic body uses to slap stop-work notices is one grey area, even the basis of defining an area as a water body has come under the scanner following the Mani Group vs Purbasha Housing Estate showdown over 32 Canal Circular Road that has now reached the courtroom.

According to the West Bengal Inland Fisheries Act, 1984, retention of water for a period of six months is enough to label an area a water body.

Last week, a tank list — drawn up on the basis of this definition — was used to slap a stop-work notice on Mani Group, which made a move to build a boundary wall around a watery tract where it was planning to build part of a giant complex for IT space.

Clearly, the definition of a water body calls for a rethink given the topography and drainage system in Calcutta.

“Parts of Behala remain submerged for at least four to five months of the year due to the monsoon. In pockets of south Calcutta close to Tolly’s Nullah and in Topsia inundation is a daily affair. Going by the definition, these areas should also be earmarked water bodies,” argued Javed Ahmed Khan, the leader of the opposition in the Calcutta Municipal Corporation (CMC).

“Some river basins in the state do not have water for more than three to four months. Does that mean they cease to exist as rivers? There is no doubt that the definition of a water body is unscientific. We need a transparent and scientific definition,” said environmentalist Kalyan Rudra.

Mani Group had moved Calcutta High Court on Tuesday to define the plot of contention as land or tank.

Mayor Bikash Ranjan Bhattacharyya, not for the first time, pleaded helplessness. “The definition we follow is a legal one and it is binding on us,” he told Metro.

“We do not want to do anything about the tank list with reference to the plot under consideration as the matter is with the court. Whatever needs to be done will be taken up after the court gives its verdict,” said the mayor.

The civic inquiry report, commissioned after the controversy erupted on Saturday with residents of Purbasha Housing Estate braving lathis, barking dogs and even some bullets fired in the air to prevent Mani Group from building a boundary wall.

“They are determined to fill up the water body illegally and destroy the ecological balance of the area. Even now after a downpour, rainwater enters houses on the ground floor. The complex will be inundated if the pond is filled up,” alleged residents of Purbasha.

The CMC’s tank list of 1998-99 defines the plot as “tank”, contradicting earlier civic records listing the same plot as “land”.

Even the mayor is upset with the way the list was prepared and then used by the department, said a CMC source.

The tank list, he added, was preserved as a secret but also used to slap stop-work notices on 412 premises in the past five years.

“If the definition of the water body is vague, there are more chances of unscrupulous builders bending the rules. The diminishing number of ponds is a proof of that,” said a member of the green lobby.