The mine was once Australia's largest zinc, lead and silver producer and the site has been operated by CBH since 2003.
The new plan includes 1.6mln silver ounces forecasted to be produced through December 2020(1).
Metalla owns a stream on 100% of the byproduct silver. produced from the Endeavor mine.
The new mine plan provides for three years of production guidance, adding 18 months, after higher metal price assumptions, mainly down to zinc, allowed an increase in the volume of economically viable reserves
"We are extremely encouraged with the success that CBH has had in their recent exploration program with the discovery of the Deep Zinc Lode," said Brett Heath, the president and chief executive.
"Additionally, higher zinc prices will allow CBH to increase their throughput over the next couple of years which should generate higher silver production for Metalla's account and support our plans for a further increase of dividends."
Based on the CBH mine plan, Metalla estimates that future production from Endeavor will be 525,000 ounces of silver in 2018; 755,000 ounces in 2019 and 320,000 ounces in 2020.
Shares in Metalla Royalty stood at C$0.81 at the time of writing