Trail bike riders are scarring the Earnscleugh tailings, a historic reserve of national significance, Department of Conservation Central Otago manager Mike Tubbs says.
Mr Tubbs said this week that trail bikes were damaging the historic gold dredge tailings.
The 160ha reserve is located between Alexandra and Clyde, along the Earnscleugh side of the Clutha River. The area is of national significance as the only ‘‘complete'' record of a century of gold dredging in Otago.
‘‘They cover the full evolution of dredging history,'' Mr Tubbs said.
They range from handstacked tailings dating back to 1863, through to tailings from coal-powered dredges, then from electric-powered dredges up until 1963.
‘‘As the different machinery evolved, the miners worked the ground in a different way, so they left a different footprint on the land,'' he said.
That footprint was in danger of being destroyed.
The reserve was fenced but easily accessible and appeared to be a target for a few motorcyclists, Mr Tubbs said.
‘‘They're riding up and down the tailings causing erosion and visual scarring and disfiguring the piles of dredge tailings.''
‘‘We need to get the message across that what they're doing is not acceptable. Not only is it damaging the reserve, but the noise pollution from the bikes is also annoying the people who live nearby.''
The trail bikes also damaged the habitat of the threatened Sigaus grasshopper, which lived in the tailings, he said.
The site is next to the Alexandra to Clyde Millennium walkway, which is popular with walkers and cyclists.
Central Otago Motor Cycle Club secretary Jo Nieper said there were tracks set up and maintained by the club that were specially designed for offroad motorcycle riders.
One was near Alexandra and the other was on the outskirts of Cromwell.
‘‘I can understand that people, especially young bikers, want to get out and ride their bikes,'' Ms Nieper said.
‘‘These tracks in Alexandra and Cromwell are open to everyone and that's one alternative available to them instead of using the tailings.''
They could also become a member of the motorcycle club and be kept informed about planned motocross events and trail bike rides.
‘‘You're never going to stop people going out and riding bikes where they shouldn't, but there are alternative tracks out there,'' she said.
