A man has been charged with indecent assault after a woman was allegedly sexually assaulted at a makeshift campground for Wildfoods Festival visitors to Hokitika.
Police said security staff at the Wadeson Island campsite "discovered the incident in progress" about 4am yesterday.
Watson said it was not a rape, but an indecent assault.
A 20-year-old Christchurch man was arrested in Hokitika several hours later. He will appear in the Greymouth District Court tomorrow.
The complainant, aged 21, was also from out of the district.