Authorities are investigating the poisoning of a section of the Amburayan River in Barangay Taba-ao, Kapangan, Benguet, after a fish kill was discovered on April 25, alarming residents.
Barangay officials said the perpetrators have yet to be identified, although the suspected dumping site of the toxic substance has already been located.
Village chair Fredo Agyao said charges will be filed once those responsible are identified, citing violations of Republic Act 8550, as amended by Republic Act 10654, or the Philippine Fisheries Code.
Authorities ruled out the abandoned Sto. Niño copper-gold mine in Tublay is the source of contamination. The site, which ceased operations in 1982, still contains legacy structures such as waste dumps, a tailings storage facility, and underground tunnels.
Water samples have been collected and submitted to the Department of Science and Technology for analysis to determine the substance involved.
The incident prompted the suspension of all recreational activities in Barangay Cuba, Kapangan, starting April 26. Construction work on the Coheco hydro project of Sta. Clara Power Corporation has also been temporarily halted due to potential health risks from contaminated water.
Agyao said no cases of livestock poisoning have been reported so far, but residents have been advised to avoid using river water for their animals as a precaution.
The suspension of activities remains in effect indefinitely, as authorities warn that toxins may persist in slow-moving sections of the river and could require heavy rains to disperse fully.