Ariana is an underground copper and zinc mining project located in the district of Marcapomacocha, Junín region, in the central highlands of Peru. It is currently owned by the Peruvian company Alpayana, which acquired it from its previous owner, Southern Peaks, in 2025.

The Ariana mining project is located in the heart of the Marcapomacocha water system, a natural and artificial infrastructure system that is the main source of water for the capital of Peru and the city of Callao, which together have more than 10 million inhabitants. This system supplies around 60% of the water consumed in Lima and Callao during the dry season. It consists of a series of lagoons, canals, reservoirs and high-altitude wetlands (peat bogs or bofedales), as well as the Cuevas-Milloc Trans-Andean Tunnel, built in the 1960s to transfer water from the eastern slopes of the Andes to the coastal area.

According to the water supplier for Lima and Callao (SEDAPAL), the project could have adverse water impacts due to: (1) a reduction in the amount of water collected, due to the interruption of groundwater flows in a porous area; (2) a possible reduction in the quality of the water collected, due to contact with heavy metals from mining operations; (3) affecting the structural integrity of the Trans-Andean Tunnel due to vibrations related to mining operations; (4) the possibility of collapse of the tailings dam, which would be located 100 linear metres from the Trans-Andean Tunnel.

The project has an Environmental Impact Assessment that was approved in 2016, and was supposed to begin operations in 2019. However, thanks to a constitutional appeal filed by a group of Lima citizens that year, the project has not yet entered the operational phase.

The ruling issued by the Constitutional Chamber of Lima in 2025, after six years of legal proceedings, establishes that the project does indeed represent a certain and imminent threat to the fundamental right to drinking water and a suitable environment. Despite this, it does not declare the Environmental Impact Study null and void (which was the plaintiffs' request) but rather calls for a Complementary Environmental Impact Study to be prepared.

In this context, Alpayana, the company that owns several mines in the area, acquired the project in 2025, a clear sign that it intends to go ahead with it despite the questions raised.