Geoscience Reference
In-Depth Information
of a natural resource belt of mountain ranges and
river valleys that surrounds the town and provides
a foundation for the outdoor adventure tourism
sector of Queenstown and New Zealand.
The river has layers of natural and amenity
values with many being outstanding in their own
right. The catchment is largely tussock grassland
with pasture development at lower altitude.
The river flows naturally some 50 km from its
source to its confluence with the Kawarau River
without being dammed, diverted or straightened
through a relatively unmodified inter-montane
basin and valley system (LINZ, 2004) with steeper
gorge sections and low-gradient reaches where it
meanders across open river flats (Plates 30, 31).
The Nevis was included as part of a WCO
application which covered the whole of the
Kawarau Catchment including Lake Wakatipu
and its tributaries. It was lodged by the Minister
of Conservation in 1990 after pressure from
whitewater kayakers and rafters and was
eventually granted in 1997 covering 10 specified
waters to be 'preserved' in their natural state and a
further 10 to be 'protected' because of outstanding
features.
The Water Conservation (Kawarau) Order 1997
recognized the outstanding recreational fishing,
kayaking and wild and scenic characteristics of the
Nevis River but it stopped short of a complete
prohibition on dams. Since 1997 both hydro-
dam proponent Pioneer Generation Limited and
conservation interests - Otago Fish and Game
Council (Fish and Game), Clutha Fisheries Trust,
Department of Conservation and Royal Forest
and Bird Protection Society - have continued to
carry out research and surveys in the valley. By
2005, Fish and Game considered there was new
information which warranted a fresh look at the
adequacy of WCO protection. With a concurrent
escalation in hydro investigations, Fish and Game
decided to seek an amendment to the existing WCO
in order to prohibit dams completely (Ministry for
the Environment, 2010a).
The application was lodged in June 2006
and sought to recognize additional outstanding
values of the river, particularly native fish and
biogeographical features related to the river's
geological history, trout fishery characteristics, and
historic sites from the gold rush era of the 1860s
onwards. The application was advertised for public
submissions in 2008 and hearings commenced in
November of that year continuing intermittently
until May 2010, with a wealth of new information
(Ministry
for
the
Environment,
2010b)
being
presented during 20 days of hearings.
Trout fishery
While the 1997 WCO had recognized that the
river sustained an outstanding recreational fishing
amenity (Plate 32), subsequent survey work
showed that the brown trout in the Nevis grew
to an unusually large size, due in part to the
food producing capacity of the low-gradient river
reaches present (Olsen and Hayes, 2002). These
trophy trout and the highly scenic wilderness
setting (Unwin, 2009) combined with pristine
water and low angler density to provide a
'backcountry trout fishery' - a challenging blue-
ribbon fishing water particularly attractive to more
expert fly anglers from within New Zealand and
from overseas.
Flora and fauna
Native fish occurring in the river are limited
to one non-migratory galaxiid species. Initially
described as
Galaxias gollumoides
or Gollum galaxias
it occurs in smaller tributary streams in the middle
and upper reaches - a distribution resulting from
the introduction of trout over 100 years ago.
Gollum is found throughout the neighbouring
region of Southland but the Nevis population
is unusual. It was considered to be the only
occurrence of the species in the Clutha River
system. This small pocket of fish is thought to
have been captured by a reversal of the river's
course caused by a tectonic uplift 500 000-800 000
years ago, described as a 'biogeographic river
capture' (Waters
et al
., 2001). Genetic studies
confirmed that the Nevis population was quite
different from other stocks of the species and it
was identified first as an 'evolutionary distinct
unit' within the wider Gollum population (Golders
Associates, 2008). However, by the time of the
