We went in there on Monday and talked to the farmer (at the dairy shed on your right as you turn onto the gravel) who said the group of paddlers in there a couple of days earlier had damaged some of the gates, creating a short in his electric fence. He said it took them the better part of a day to track down and fix the issue, leaving him out of pocket and wasted time.
He's looking at putting on a charge of $50 per paddler per year to get access beyond the top carpark by the shed where the DOC track starts.
I reckon it's easier for us all to pay couple of beers/token donation to say thanks for maintaining the track than have to worry about sorting keys and paying for them!
Don't be a dick, respect his land, stay in his good books by asking permission, our experience is he's very friendly if you pop in to the dairy shed, especially with a cold one ;-)