The alien landscapes of the Mackenzie Basin
They've been likened to crop circles, mysterious shapes which appeared out of nowhere.
Others just call them "green stains."
Irrigation circles have taken over the Mackenzie country, turning thousands of hectares of high-value, golden tussocked land into splotches of vivid green.
The desert-like South Canterbury region is the driest part of the country, meaning large-scale farming requires intensive irrigation.
The resulting circles can each be up to 2 kilometres wide, roughly the size of Christchurch's Hagley Park. There are dozens of them across the district.
They almost entirely cover both sides of the road along an 8-kilometre stretch between Twizel and Omarama.
Irrigation has fundamentally altered the area's golden hue, which had seen it used for Hollywood movies and tourism promotion.
Peter Jackson picked the area to stage the battle of Pelennor Fields, the climactic battle sequence in the Lord of the Rings trilogy. He returned for The Hobbit, using Lake Pukaki near Twizel as the setting for Lake Town.
Environmental group Forest & Bird has criticised the "intrusive visual pollution of the Mackenzie landscape", which it says has an impact on the varied wildlife in the area.
The unique wildlife in the basin include the kaki, one of the world's rarest birds, which is only found in the Mackenzie; the wrybill, the world's only bird species with a bent beak; and the alpine weta, which freezes during the winter and survives by thawing in the summer.
Forest & Bird says irrigation reduces river levels, and intensive farming causes nitrogen to pollute waterways inhabited by species already under threat.
An environment report released last week showed nitrogen levels produced by dairy intensification had risen 12 per cent since 1990.
Dr Ann Brower, senior lecturer at Lincoln University, said increasing irrigation was linked to the tenure review process, which had been "quietly transforming the South Island high country".
High-country land had historically been Crown-owned and leased out with conditions preventing irrigation and development of the soil without express permission.
The tenure review process had seen large portions of the land placed into private hands, opening it up to intensification.
"While under pastoral lease, land use is strictly limited. Once freehold, it's up to the RMA and the district," Brower said.
"Many of the districts couldn't have anticipated free holding, so didn't have restrictions in place in the plan."
The process is viewed by some as controversial, and has seen formerly Crown land valued at $154 million sold into freehold since 2011.