200 workers at Koolan Island mine have been made redundant as the company tries to find a solution for its flooded operation.
Workers were stood down at the time of the incident and all activity in the pit was suspended, along with all non-essential activities on the island.
Today, Mount Gibson said the mine would be placed into care and maintenance until further notice.
It said an assessment of the cost and timing to rebuild the seawall was underway, but that any option would hinge on iron ore prices and exchange rates.
The company said it will provide outplacement assistance to affected employees and pay all entitlements in full.
It is believed redundancy costs will amount to $11 million.
Mount Gibson said it will provide an update on the reopening of the mine in the first half of 2015.