Barrick Gold's $8.5 billion Pascua Lama project is about to get more expensive.

The mining giant last upped the estimate in November, but most analysts agree this is now an outdated figure considering what has happened since – namely environmental opposition leading to shut down and Barrick agreeing to build a new water management system.

This would be the fourth time the company has re-evaluated Pascua Lama's price tag. Initially the figure was up to $5.0 billion. In July 2012 it was "as much as $8.0 billion," Reuters notes. 

As of June 2013, Barrick had spent $5.4 billion.

The mining giant took a $5.1 billion impairment charge on the project in the last quarter but also announced a deferral of planned capital spending for the year of between $0.7-$0.8 billion.

Analysts interviewed by Reuters say the change could result in overall costs rising by "a billion dollars or more."

"That number could be massive," an analyst at Salman Partners told Reuters. "When you're talking about re-engineering a project, all bets are off. Nobody really knows."

Read More: www.mining.com/investors-eager-to-see-how-much-more-pascua-lama-will-cost-89758/