The March 31 torrent of earth killed 316 people including more than 100 children after three rivers flooded near the Amazon town, according to authorities.
Environment Minister Luis Alberto Murillo announced that the at-risk area where the Mocoa tragedy occurred will be declared "a total protection zone, which means that from now on, no (industrial) activity can be carried out there", a government statement said.
El Tiempo newspaper earlier quoted Murillo as saying in an interview that "there was deforestation for farming and livestock without observing the required environmental protections and reserves".