Bengaluru: The Karnataka Lake Conservation and Development Authority and other local agencies believe the fire at Bellandur lake may have been set off by those who graze livestock in the grasslands. Either the fire could be accidental or intentional to clear the way for new grass to grow in the burnt area.

However, as experts pointed out that accumulated methane in the sewage-laden sludge of the lake could have aggravated the fire, the Karnataka State Pollution Control Board (KSPCB) on Saturday took samples from nine locations to determine the methane content.

“We will have results on the gaseous build-up in the soil within 15 days. However, when we had tested the samples in February 2017, we had found low levels of methane. The spread of the fire could be because of the overgrown grass that has dried out,” said KSPCB chairman Lakshman.