Isthmus

Nature in the
sublime.
Mokihinui.

Approach

In 2008, a hydroelectric dam was proposed for conservation land on the Mokihinui River on the South Island’s West Coast. Building the dam require the inundation of the Mokihinui Gorge, which provides entry to a pristine inland basin surrounded by mountains. Following initial approval of the application, the Department of Conservation (DOC) and other parties, including Isthmus, took a successful appeal to the Environment Court.

Below Mokihinui catchment. The Mokihinui landscape was seen from a design perspective as a distinct landscape that holds together as a whole (a single, strong idea) and, at the same time, contains a rich variety of geology, landforms, vegetation types, and experiential responses.

Mohikinui is a whitebaiting settlement at the mouth of the Mokihinui River, high on the shoulder of the West Coast. Follow the river back through the Mokihinui Gorge and you’ll find a large and near-pristine catchment surrounded by mountains. It is a distinct and self-contained wilderness, structured by a rich variety of landforms, containing dramatic natural features and a natural blanket of vegetation that segues from alpine snowgrass to warm coastal forest of northern rātā and nīkau palms.

Below and right The lower reaches of the Mokihinui River at Seddonville, just below the Mokihinui Gorge. Mokihinui settlement at the mouth of the river.

The Mokihinui is a museum of landforms: in the east there is the Thousand Acre Plateau, a snow tussock-covered limestone slab perched above rim-rock cliffs and pocked with sink- holes; the western range, in contrast, is glacier-carved granite with sharp peaks, tarns cupped in cirque basins and deep, u-shaped valleys. Between the two ranges, rivers tumble through beech-forest-lined gorges, squeeze between limestone peaks and converge on an inter-montane basin. Here, the two main branches of the Mokihinui River spread out to braided meanders on an alluvial plain before plunging into the head of the 14-kilometre Mokihinui Gorge. The gorge descends through limestone, greywacke, schist and granite, through rapids and deep pools, before emerging to the coastal plain a short distance from the rollers of the Tasman Sea.

“The gorge and upper catchment landscape can be described in aesthetic concepts of ‘wilderness’. It has a vast scale enclosed by mountains, is clothed in natural vegetation, contains wild rivers and is subject entirely to the forces of nature. Human elements are insignificant. It is a landscape setting in which one could experience an escape from the everyday world, contact with nature, solitude and physical challenge.”

— Gavin Lister, Isthmus

Mokihinui also has historical associations. Gold miners once eked out their trade between the walls of the gorge and under the vast skies of the inland basin, connected by a pack track that provides passage through the gorge.

To the dismay of many, in March 2008 an application was lodged for a dam and hydroelectric power station that could generate up to 360 gigawatt hours of electricity a year but would flood the 14-kilometre-long Mokihinui Gorge. Following an initial approval in 2010, DOC and other parties lodged appeals with the Environment Court. DOC’s opinion was that the Mokihinui River Gorge was a highly unmodified river system of regional and national importance. Isthmus’s Gavin Lister was one of the experts called upon by DOC to provide evidence.

Below and right
Mangatini Falls cascade from the Stockton Plateau into Charming Creek, in the vicinity of the transmission line route proposed for the dam. Limestone ‘flatirons’ create a row of shark’s teeth across the west side of the inter-montane basin.

The case provides a clear example of the tensions between development and preservation. The dam proposal had some local support – the cost of electricity on the West Coast is high when it is compared to other parts of New Zealand and, potentially, the region’s commercial interests could be exposed if the single transmission line bringing power to the region were damaged.

Team Members
Gavin Lister,
Past Team Members

James Bentley, Grace He

Collaborators
Andrew Cameron
Auckland University – Prof Paul Williams
Wildland Consultants – William Shaw, Dr Kelvin LLoyd, Kath Walker, Dr John Leathwick, Cathryn Barr

Client
Department of Conservation