Hi Eds84,
"Activities" (trades, businesses or occupations which would include concerts by musicians) on DOC managed land is very common. Mining is very common on DOC managed land. There's a good guide published by DOC if you're interested in making your own application
http://www.doc.govt.nz/Documents/ab...guide-mining-activities-conservation-land.pdf
The thing is, you need a concession to carry out an activity on DOC managed land (conservation land, reserves, etc):
http://www.legislation.govt.nz/act/public/1987/0065/latest/DLM104640.html
DOC can grant everything from a permit, lease, licence or all the way up to a registered easement for activities.
NTL has been granted a concession to use the land for mining and indeed DOC has also given NTL permission to secure the site.
I agree with you that the idea of running a public event for musicians, for the pecuniary (membership fees, advertising, etc of PK and musicians) and non-pecuniary gain (reputation, etc) seems to fall fowl of s 17O(2) of the Conservation Act 1987:
http://www.legislation.govt.nz/act/public/1987/0065/latest/DLM104635.html
Which is why, if you are a concerned citizen, you can always send through a complaint to DOC about the activity that does not seem to be the subject of a permit. Here's a link to the Hauraki DOC office:
http://www.doc.govt.nz/footer-links/contact-us/office-by-name/?mode=details&office=2769
Have fun
