Bangalore, Jul 8 (IANS): With massive residential and commercial complexes continuing to come up around Bangalore's lakes, demands are getting louder to regulate such construction to save the precious water bodies.

"Near water bodies we must not allow such complexes to come up," Bangalore Political Action Committee (B.PAC) vice president and former Infosys director T.V. Mohandas Pai told IANS.

"We must come with a plan to harvest water in these water bodies, not allow sewage to flow there and accumulate, treat waste water and reuse it and prevent leakages in the pipelines," he said when asked whether there should be a ban or at least restrictions on building such huge complexes in spite of Bangalore's growing water scarcity.

Bangalore which had over 900 lakes in the early 1950s, is now left with only about 200 and more than half of them are heavily polluted with sewage. Preserving these 200 lakes is becoming of prime importance as a looming water shortage stares the city, which is heavily dependent on supplies from the Cauvery river.

The rapid growth in the city's population since the 1990s, when it became the nation's IT hub, and exploitation of ground water to meet the growing need has resulted in a steep fall in the groundwater level.

In a large part of the city, groundwater is not available even at a depth of 1,000 ft.

The water shortage and the continuing growth as evidenced by the massive residential and commercial complexes coming up are also raising apprehensions that half the city might have to be evacuated in another 10 years if remedial measures are not taken at the earliest.

"A city dies when its lakes die," former Karnataka additional chief secretary V. Balasubramanian told IANS.

Urging Bangaloreans to take responsibility for the survival of their city, he warned that if this is not done, half of the city "might have to be evacuated in 10 years due to water scarcity, contaminated water and disease".

Balasubramanian was skeptical of government organizations like the Karnataka Lake Development Authority and the Karnataka State Pollution Control Board being effective in preventing growing threats to the city's lakes even if seeking their nod for construction around lakes is made mandatory.

"Both of these are totally ineffective bodies and their permissions mean nothing. Only PIL (public interest litigation) in the high court can result in some action," he said.

"The lakes in Bangalore should be protected. No residential complexes should be allowed to come up near the lakes," Centre for Symbiosis of Technology, Environment and Management (STEM) managing director V.M. Hegde told IANS.

STEM is a Bangalore-based not-for-profit organization engaged in organizational research and development planning.

"All possible care has to be taken while preparing/revising the master plans by the BDA (Bangalore Development Authority). If any development is allowed near the lakes, it should be withdrawn and the lakes protected," said Hegde, a retired director of the Karnataka town planning department.

A recent study by T.V. Ramachandra and his team from the Energy and Wetlands Research Group of the Centre for Ecological Sciences at the Indian Institute of Science, noted that "intense urbanisation and urban sprawl" was the reason for the disappearance or decline in the number of Bangalore's water bodies.

The study says many lakes were encroached on for illegal buildings, a number of lakes were sewage fed, lake catchments were used as dumping yards for either municipal solid waste or building debris; multi-storeyed buildings have come up on some lake beds.

Among the threats to Bangalore's water bodies are encroachment of lakebeds and the lakes themselves, lake reclamation for infrastructure activities, unauthorized dumping of municipal solid waste and building debris and sustained inflow of untreated or partially treated sewage and industrial effluents.