The seawater will replace the use of fresh water at the copper project. It will also meet higher water demands anticipated in the company's definitive feasibility study, to be released next year. The DFS projects an upscaled 50,000-tonne-per-annum copper cathode project.

The power supplier would use seawater in its cooling systems at an electricity plant in Mejillones. The recycled water would then be used at the copper project.

The agreement is for five years, with the ability to extend by two years.

Marimaca Copper did not specify the power supplier.

The agreement allows Marimaca Copper to continue permitting and technical studies, including in-progress water pipeline studies.

The water supply agreement will be at a lower cost than originally projected in Marimaca's preliminary economic assessment (PEA) in 2020.

The agreement also secures power supply for the mine's pumping infrastructure, and includes an option to provide 10% of Marimaca's operational power needs.

"The use of seawater, as well as the green power supply commitments provided by our partner, represents a significant achievement with respect to the Sustainability Commitments we launched earlier this year," Marimaca Copper chief executive Hayden Locke said.