The field has been closed since Tuesday, when high levels at an oxidation pond forced management to close because of a risk wastewater might overflow.
A drainage operation, involving a convoy of water tankers which have trucked wastewater to a disposal facility in Queenstown, has been under way for the past three days.
Cardrona media spokeswoman Nadia Ellis said the skifield would not be able to open as hoped today. Managers had extended their plans to reopen until tomorrow.
A cautious approach was being taken because Cardrona did not want to risk any potential environmental contamination landing below the skifield.
Australian visitor Geraldine Pulver, of Tasmania, approached the Otago Daily Times yesterday to complain about the closure. She bought early bird season-passes to ski at Cardrona in March for a three-week holiday, which her family is halfway through.
She was angry about privileges being extended to Cardrona holiday-makers staying in the skifield's apartments, who are still able to ski the mountain.
Ms Ellis confirmed visitors booked into the apartments had been able to continue using the skifield, as had a film crew that has been based on the mountain.
"It is a small group of people who have already booked and paid for the use of on-site accommodation," she said.
The number of people and any effects from wastewater they might create were considered negligible, Ms Ellis said.
"We totally understand the frustrations of people who can't come skiing at Cardrona. We are sympathetic to the situation and are very disappointed we can't open," she said.
Refunds are available for customers affected by the closure, who have bought certain skifield services and lift-pass tickets.
Cardrona was doing its best to ensure it was being responsible about the environmental risk it was managing regarding the wastewater pond, she said.
The ramifications of closing the skifield were "nothing compared to the the fallout" of a wastewater overflow, she said.
"We've certainly lowered it, but we want to make sure the pond is down to a level where a busy day on the skifield won't pose any future problems," Ms Ellis said.
Cardrona was doing "all we can" to keep people informed through its website, blog announcements, and Twitter messaging services, about resuming normal operations, she said.
