The Queensland floods, which on January 5 caused a steam outage at the Lytton Refinery, prompting an unscheduled shutdown, is expected to cost Caltex Australia (ASX: CTX) $5 - $10 million (after tax) in 2011. The company is continuing to assess the impacts of the severe weather conditions.

Caltex said it has been undertaking a process to return the refinery to normal operations while also completing scheduled maintenance that had originally been planned for later in the year.

"Despite the floods reaching Brisbane, neither Lytton Refinery nor Lytton Terminal has been directly affected. This has allowed the start-up for the refinery to continue as planned," Caltex said.

According to the company, partial production will re-commence tomorrow and will progressively increase over the next 10 days. Full operation of the refinery will be dependent on Brisbane Port operations, which are currently suspended due to the flood situation, returning to normal.

The magnitude of the flooding in Queensland and northern New South Wales has meant Caltex has had to adjust its normal supply chain in order to overcome accessibility issues in affected areas.

Caltex said its teams are working to ensure supply to the Lytton, Gladstone, Mackay and Cairns terminals continues despite the major challenges. Sales volumes have been impacted in those areas affected by the flooding but the financial impact of this is not expected to be material.

Shares in the company lost nearly 6 per cent to be the worst performer on the S&P/ASX200 on Wednesday, closing down 85 cents, or 5.67 per cent, to $14.14.