Mr Morgan said on Twitter yesterday: ''My apologies to Wanaka residents for the burn-off on Hillend yesterday. Looked bloody horrible, I know.''
He did not respond to further inquiries by the ODT.
Otago Regional Council director of regional services Jeff Donaldson said the council had received ''quite a number'' of complaints and was carrying out ''a full investigation''.
While the fire was permitted by the Otago Rural Fire Authority, Mr Donaldson said it still had to comply with the council's air plan.
''If smoke is obnoxious beyond the boundary, then it is considered that it would be an offence.''
Mr Donaldson said that under the air plan, the council had an obligation to investigate a burn-off, just as it did domestic fires and backyard burning.
A council staff member was on the scene on Tuesday photographing and smelling the smoke, he said.
''That information is being sent to Dunedin for myself and my senior staff to look at and decide what we do further.''
The staff member was a ''warranted officer'' so was an expert witness for the purposes of the Resource Management Act, Mr Donaldson said.
The council had issued infringement notices and taken prosecutions over burn-offs in the past where smoke was considered ''offensive and obnoxious'' beyond the boundary.
A spokesman for the fire authority said yesterday it was not planning to take any further action.
During the fire, Hillend manager Mike Scurr told the ODT a lack of wind caused smoke to accumulate, but the burn-off was well controlled and had gone to plan.
Upper Clutha Vegetation Control Group chairman Alan Kane considered bad luck had played a part in the smoke issue.
''It looked to be heading in the right direction when he lit it and it seemed to stop and almost be a southerly drift, which couldn't have been worse from Wanaka's point of view.''
His group was set up to improve understanding of burn-offs and to ''encourage farmers to use other methods wherever practical so as to phase out the necessity to burn''.
''I think that trend is happening. There is less and less burning taking place.''
He understood Hillend station was engaged in a long-term development plan that would ''substantially reduce or eliminate the need'' for burning.
Mr Kane declined to predict how long it would be before burn-offs in Otago ceased entirely.
In reference to Mr Morgan's apology, one of the most vocal critics of the burn-off, Jo Gumpatzes, of Wanaka, said it was ''nice that he's acknowledged there should have been an apology''.
Ms Gumpatzes said she understood the reasons for burn-offs but questioned whether farming mountains was a ''viable proposition''.
''For the sake of the few sheep they do run up there, is it worth it?''
