However, the society said it was a "bit surprised" at the amount and warned it would bankrupt the group.
In his decision, sent to the parties on Wednesday, Judge Laurie Newhook, of Auckland, ruled the Gary Mullings Family Trust could apply for costs of $8000 from July 9 to 14 of the proceedings.
Trust spokesman Gary Mullings said the family did not claim for costs before those dates.
"The judge considered a higher than usual award of costs is justified and awarded us 80% of that amount," Mr Mullings said.
"I'm delighted the judge has seen that it was another frivolous waste of everybody's time and money. Even though [Wakatipu Environmental Society Inc spokeswoman] Karen Swaine commented in the press that she withdrew because because of financial reasons, I would find that very hard to justify as only somebody who doesn't win has to pay costs."
Ms Swaine said Wakatipu Environmental Society Inc (WESI) felt the amount awarded was "excessive".
"We're a bit surprised by the amount, given the little amount of time undertaken by the trust's representatives."
Ms Swaine said the society would not be appealing the judge's decision.
A letter from the WESI solicitor to the trust's solicitor that explained the payment of $6434 would bankrupt the society and "looked for a way forward" was drafted yesterday.
The letter would be circulated among members for approval before being sent to the trust.
Mr Mullings said Ms Swaine and the executive were told they would be responsible for costs by the judge and the family trust before the society took the matter to court.
He said if WESI did not have the money, "the only people who would suffer will be the children of Arrowtown. I've already committed approximately 50% of the costs to computerise the school library."
The Environment Court in Auckland said it would release the judge's decision to the media on Monday.
