A complaint was received in May 2005 by a local chapter of a federation of commercial fishermen regarding the Minera Antamina Project’s port facility and its impact on the marine environment. It is the second CAO complaint regarding the port facility. This complaint alleges that the port facilities are negatively impacting the marine environment at Huarmey Bay, and expresses concern that the facility is discharging waste water into the bay and spilling metal concentrate into the bay. The complainant also proposes a bio-monitoring project to evaluate the marine environment around the port facilities that would involve cultivation and analysis of mussel beds.

MIGA has a series of guarantees with the project that were signed in 1999.

In June 2005, CAO appraised and accepted the complaint. During an assessment trip to Huarmey, CAO met with the complainants, Antamina representatives, and members of a local monitoring committee that oversees a data and information operation relating to the port facilities. CAO also met with several Peruvian governmental organizations as well as the MIGA project team for Antamina. An independent hydrologist under contract with CAO conducted a technical review of the marine environment as part of the assessment.