An oxidation pond storing stormwater and grey water at the Cardrona resort, near Queenstown, came close to overflowing this week after heavy rain and a snow melt.

Contractors have been called in to drain the facility, but it could take some time.

Sewage is not involved. It is stored separately before being transported from the site.

A note posted on the resort’s website yesterday reads: "Unfortunately we will be closed for the next few days while maintenance is carried out on our oxidation pond".

Management says refunds will be made to people who’ve pre-booked multi-day lift pass tickets, ski and snowboarding lessons and consecutive days of equipment hire.

The closure is seen as a big blow for the resort, coming at the height of the season after good falls of snow.

A major upgrade of the oxidation pond has already been scheduled for the coming summer.