Its 148-page report for Environment Minister Amy Adams was made public yesterday and two of the three commissioners recommended a complete prohibition on damming.
Judge Jon Jackson took a different view and recommended the potential for a small dam on the river be left open, subject to certain conditions. Both series of recommendations - the majority view by Commissioners Kathryn Edmonds and John Mills and the minority view by Judge Jackson and the reasons behind those views - will be forwarded to Ms Adams to make a final decision, ending seven years of debate on the matter.
The main protagonists, the Otago Fish and Game Council and energy company Pioneer Generation, received the report late yesterday afternoon.
While the council was optimistic the majority recommendation would carry the most weight with the minister, the energy company said it was too soon to comment on whether a potential dam on the river was a ''lost cause''.
The debate began in 2006 when the New Zealand and Otago Fish and Game Councils applied for an amendment to the Water Conservation Order to rule out hydro dams on the river.
The application attracted about 250 submissions and was heard in 2009-10 by a special tribunal appointed by the Ministry for the Environment.
The tribunal decided the conservation order should be changed to prohibit damming and diversion to protect a native galaxiid fish, a species found only in the Nevis River.
Its finding was challenged by three parties - Pioneer Generation, which had plans for a small hydro dam on the river, the fish and game councils and recreational kayaking group Whitewater New Zealand.
The Environment Court heard the matter over six days in October and November last year. Otago Fish and Game Council chief executive Niall Watson said yesterday although Judge Jackson put his recommendation forward ''we have to feel confident that the majority decision will be given the most weight and rely on that prevailing''.
The recommendation by Commissioners Edmonds and Mills, together with the earlier agreement the entire Nevis Valley should be reclassified in the Central Otago district plan as an outstanding landscape of national importance, was a ''major improvement'' on the protection the area had in the past, Mr Watson said.
The majority recommendation gave a high level of protection to the river's angling amenity and its other outstanding natural and recreational values, including kayaking.
It also recognised the river landscape of the Nevis Crossing by defining it as ''wild and scenic'' rather than just ''wild''.
''The other important point is the community support for this. Of those initial 250 submissions, nearly all supported a prohibition on damming. The only dissenting voices were Pioneer, Contact and the local bodies,'' Mr Watson said.
Pioneer's asset manager, Peter Mulvihill, said the company's staff and legal advisers were still analysing the report and its ramifications.
''We're a little perplexed as there's two varying opinions and two quite separate recommendations, but we're satisfied Judge Jackson has considered a lot of our evidence as being relevant,'' Mr Mulvihill said.
Asked if Pioneer's plans for a dam were ''a lost cause'', he said it was too soon to comment.
''Obviously, we're taking legal advice about the recommendations, so I don't know about that yet.''
Commissioners Edmonds and Mills said any dam would cause a significant adverse effect on the landscape and also affect the kayaking amenity.
A hydro dam was not needed for local power supply security and the hydro potential of the Nevis was relatively insignificant in the national and regional context, they said.
They did not believe a prohibition on damming was essential to protect the Nevis galaxiid, but said the conservation order should be amended to ban damming because of the negative effects on the outstanding values and characteristics of the river.
Judge Jackson said the order should be amended to protect the galaxiid's habitat, but the possibility of a small dam below the Nevis Crossing should be left open, subject to conditions.
Ms Adams should not change the order as requested by the majority of the court and instead should allow for a potential small dam below the Nevis Crossing but above Potters Creek, he said. The court was not unanimous in its decision, so a single report and recommendations was not possible in this case, Judge Jackson said.
