The New Zealand Historic Places Trust (NZHPT) has confirmed that an agreement, made public at the time of its conclusion, was reached with Meridian Energy last year to mitigate effects of its proposed Project Hayes wind farm in Central Otago.

The written agreement detailed ways Meridian Energy would mitigate developmental effects on historic and archaeological sites on the Lammermoor Range project. The amounts concerned were earmarked to cover the cost of particular projects that directly mitigate the impact of the project on the heritage values of the wind farm site. These costs have a maximum value of $179,000 and were negotiated prior to NZHPT agreeing to withdraw its Section 274 Environment Court appeal against Project Hayes.

No money will be paid unless the project proceeds.

NZHPT chief executive Bruce Chapman said a media release was issued to the Otago Daily Times in May last year indicating an agreement had been reached with Meridian Energy on a range of mitigating measures that satisfactorily addressed NZHPT concerns.

The following month the agreement was sent to the Otago Daily Times under the Official Information Act which ran a prominent article on June 16.

NZHPT concerns specifically related to the effects of the proposed wind farm on the heritage values of the Old Dunstan Road, including protection of the archaeological features such as old gold workings and visual protection of the Dunstan Trail as a heritage road.

Mr Chapman strongly refuted the allegation that the deal had been secret, and noted that the negotiation of agreements of this nature is common practice with Environment Court appeals.

"NZHPT works to try to ensure the best outcome for heritage values," Mr Chapman said.

"Entering into agreements of this nature require consideration of the cost of pursuing the appeal, the likely outcomes from the Court and the willingness of parties to negotiate."