Peru's Environment Ministry has declared a 90-day emergency to clean up 21,420m3 of toxic mine tailings that spilled late last month into the Opamayo River.
The spill occurred on 26 June when a containment dam at the Caudalosa Chica mine collapsed, unleashing cyanide-tinged wastewater into the Opamayo River, which flows into the larger Urubamba River.
Animals and wildlife situated 70km away from the mine have been badly affected by the outpouring of toxic metallic waste, prompting officials to issue the alert.
The spill has affected more than 1,500ha of land and contaminated the Huachocolpa River with 50,000m3 of debris, according to Huancavelica's local National Water Authority.
Over 700 miners have been involved in the clean-up operation, the ministry said.