Karnataka has imposed Rs 140 crore in penalties on 13 iron ore mining companies in Tumkur for encroaching on government land and dumping mineral waste, thereby causing damage to the environment. "We have conducted a suo motu joint survey with the departments of mines and geology, forest and revenue in Tumkur district and found that 13 iron ore mining companies have violated the Karnataka Land Revenue Act, 1964, by dumping mineral waste on government land," C Somashekhar, deputy commissioner of Tumkur, said.