A lake’s death by drowning

The crater was created by a hypervelocity meteoric impact some 50,000 years ago.

Experts are worried over the increasing water levels in the crater that is diluting the salinity of the natural salt water lake. Unchecked sewage flowing into the lake and unmindful felling of trees is threatening the unique ecosystem that Lonar has spawned. Protests and and sporadic rescue plans have changed little.

Lonar has a history which is as alluring as the crater itself. According to one theory, a massive meteor entered the earth’s gravitational range at a speed of 90,000 kmph, ramming the earth’s surface. It is said to have released energy equivalent to a six-megaton atom bomb. Such was the impact that rocks shot up to 20 metres, leaving a massive crater 170 metres deep and 1.8 km in diameter.

Scientific research on Lonar started after the lake was first noticed by Englishman C J E Alexander in 1823. In 1896, American geologist G K Gilbert conducted studies to prove that Lonar was the creation of a meteoric impact. Much later, an on-the-spot study by the Geological Survey of India (GSI), United States Geological Survey (USGS) and other agencies under the leadership of K Fredrickson, used cosmic-ray dating to determine that the lake was 50,000 years old.

Scientists maintain that the Lonar rocks are similar to moon rocks. Studies by the Smithsonian Institute, GSI and USGS confirmed the crater’s meteoric origin. The results were published in 1973.

Lonar is the oldest meteoric crater in the world. According to scientists, its nearest rival—the Canyon-Diabolo of Arizona in the United States is younger by 230 centuries. In size, the Lonar crater stands after Bosmatvi lake in Ghana which has a diameter of 10 km and a lake in New Quebec in Canada with a diameter of 3.5 km.

The lake at the bottom has a unique micro ecosystem that has led to evolution of new life forms which endure salinity that is even higher than that found in sea water. Lonar lake has brackish water, dominated by spirulina— a blue green algae which scientists say is rich in nutrients. Pune-based botanist Dr P K Ghanekar in 1996 has recorded 14 types of algae in the lake. The relatively undisturbed surroundings also attract many birds and support a rich insectlife.

Scientists of the Pune-based western regional station of the Zoological Survey of India (ZSI) have reported three rare spider species and two scorpion species from the area.

According to ZSI scientist Dr P P Kulkarni, the lake is now showing some disturbing trends. Past records show that the crater water was extremely saline with its pH content reaching 12.5. That is dangerously changing now.

ZSI scientists who returned from Lonar last week report that the water quantity in the lake has almost doubled.

‘‘As a research student I used to climb down right up to the base of the crater, but now water levels have clearly increased,’’ says ZSI scientist Dr S G Patil.

Scientists attribute the rise in water levels to water coming in from an irrigation department reservoir and also to sewage flowing into the lake. Buldhana district collector Dinesh Waghmare has pressed for more studies on the increasing water levels. ‘‘The reservoir can not be blamed conclusively,’’ says Waghmare, adding that the district administration is waiting for Maharashtra government to allot necessary funds for a project to stop sewage flowing into the lake.

The Maharashtra Tourism Development Corporation (MTDC), however, has planned a Rs 5 crore project for Lonar with Japanese aid. The MTDC has proposed to protect the crater by banning all activity within a stipulated distance from the lake.

As the government decides on its plan of action, Lonar awaits badly needed help to keep its unique ecosystem afloat.