The wildlife authorities in Rajaji National park, have tried everything from traditional medicines to modern methods of treatment, before deciding to put her down.
"In our wildlife Act, there is a provision that the wildlife warden has the power to take such a decision when an animal becomes so ill that it is unable to recover," said G.S. Pandey, Director of the Rajaji National Park.
The news has created a stir in the city as hordes of people are flocking the park for a glimpse of the much-loved animal.
The sight of Arundhati writhing in pain and tossing in discomfort is generating lot of sympathy among the residents who come to bid goodbye to her.
Meanwhile, the decision for mercy killing has sparked protests from animal activists who term it as unethical resulting in prolonged agony for the animal.
But some of the residents defended the decision to kill the elephant.
"People who are protesting against its mercy killing are wrong. The only option left for relieving the animal of the agony is to grant her mercy death and relieve her of the pain," said Mahavir Rahila, a resident.
Arundhati who came to Rajaji Park in 1981 is the biggest and oldest among five elephants. She has been a favourite with the guests and staff.