The company started its water management programme in September 2020 to improve knowledge of the mine's water system and also to improve the effluent leaving the mine for the US Environmental Protection Agency's Central Treatment Plant, or CTP.

"The recently commissioned pre-treatment system achieves this goal by reducing significantly the amount of treatment required at the CTP, and the associated costs, before the mine water is discharged into the south fork of the Coeur D'Alene River," Bunker Hill said of the most recent addition.

"The company's new pre-treatment system is removing over 70% of the metals from water before it leaves the mine, with the potential for further improvements."

The miner said that, by keeping acidic water at the mine site from mixing with the cleaner water, the mine can focus on treatment of a smaller stream of effluent, which in turn reduces the cost and scale of treatment.

In addition to the benefits for the mine's restart, it also underpins Bunker Hill's licence to operate with its zero-footprint techniques for environmental benefit. Currently, the company is awaiting the operation's PEA, but said the report is on schedule for delivery in the early June quarter.

"Managing our mine water discharge is an essential part of a strategy designed to rapidly re-start the Bunker Hill mine as a low cost, modern, and sustainable operation," CEO Sam Ash said.

"Together with our high-grade silver exploration program and delineation of our maiden NI 43-101 compliant resource, the successful commissioning of our pre-treatment plant marks another key milestone in achieving this goal and highlights our new team's technical capabilities."