After a flyover of the region showed an abnormal orange stain in the water, authorities in northern Mexico have issued a new alert of a toxic spill in the Sonora River basin from a copper mine operated by Grupo Mexico, the state director of civil protection said Sunday.

According to news reports, the Sonora state civil protection agency said it was ending its relationship with mining giant Grupo Mexico because it was continuing to discharge toxic substances into the river, even after a devastating spill in August of around 10 million gallons of acids and heavy metals contaminated two rivers and a dam downstream.

Farmers in the region are already struggling as a result of the August disaster, which "paralyzed" the agriculture and ranching industries and left 22,000 people along the river without a regular running water supply, Al Jazeera reported last week.

Carlos Arias, director of Sonora's civil protection agency, said the latest spill was an "intentional criminal action," according to reporting by Regeneración, a Spanish-language publication devoted to social justice and environmental causes.

Grupo Mexico, which has been accused of lying about clean-up and containment measures and of lax supervision at its $1-billion-a-year Buenavista mine, blamed the new spill on heavy rains caused by Hurricane Odile last week. The company created a $147 million fund to help mitigate damages from the prior spill, was fined $3 million by the government, and has denied any wrongdoing.

But Arias said at a press conference that since the August spill, the mining operation has "blocked access to investigators, and he warned Sonora state authorities would come back—this time backed up by security forces," Agence France-Presse reports.

"We will act with the full weight of the law, because they are already in a plan that cannot continue," Arias said, adding the government was mulling permanent closure of the mine, one of the largest in the world.