Doc is standing by the confidential 2007 deal, which reportedly involved a payment of $175,000 by Meridian to the department in return for DOC not opposing the wind farm proposed for 92sq km of the Lammermoor Range in Central Otago.
The parties agreed Doc would drop all its outstanding issues in relation to Project Hayes and adopt a neutral stance on the project.
Meridian Energy refused to comment on the deal.
Doc's Otago Conservator Jeff Connell was standing by the agreement, Radio New Zealand reported.
The Environment Court has been hearing submissions over a bid by Meridian to gain resource consents for the $2 billion windfarm.
Conservation Minister Tim Groser and Green Party co-leader Jeanette Fitzsimons told Radio New Zealand today they had only recently been made aware of the deal.
Mr Groser said the agreement had happened on the previous government's watch and the National Government would reserve its position until it had all the facts.
However, he said the issue had a broader context, which was that power providers were struggling to increase generation to keep pace with growing demand.
Part of that was because of difficulties in getting consents to start new projects, and plans were already in place, in the form of Resource Management Act (RMA) reforms, to try to improve the situation.
Ms Fitzsimons said the issue of bartering over developments was not new, and was an ongoing saga of development and conservation clashing.
"Doc never wins that argument and so for years, and over many projects, we've had Doc muzzled in terms of giving its input to the Environment Court."
She said Doc had a large amount of information about the possible effects of certain projects and keeping out of Environment Court appeals meant hearings lacked vital data and were skewed.
While there were many options in terms of mitigating conservation damage, money changing hands in secrecy for silence was unacceptable.
"Doc is obviously going to do something with the money, and they're going to do something of environmental benefit.
"But that should not have been a secret deal and it should not have been at the price of buying Doc's silence."
She said she was drawing a distinction between Meridian making a payment in recognition of the environmental effects, and Meridian paying money to shut DOC up.
"And that is what is absolutely unacceptable." Mr Groser's comments had given her no comfort that Doc would be allowed to have a say on public projects in the future, and National's approach to the RMA was to reduce public participation in development decisions, she said.
"So I don't think local communities concerned about big developments in their area are going to get much comfort out of that."
The appeal hearing on the Project Hayes consents resumes in Queenstown today.
