Lake Manapouri - Integrated Management of The Lake

Integrated Management of The Lake

The environmental movement of Save Lake Manapouri Campaign, is considered to be the first Environmental movement in New Zealand. When this movement won the campaign to stop levels on the lake being raised, the government formed the Guardians of Lake Manapouri and Te Anau. This meant that main campaigners during the Save Manapouri Campaign were appointed to advise the managers of the hydro-electric power plant on the management of both Lake Manapouri and Lake Te Anau. This holistic management between nature conservation and hydro-electric development was unprecedented in New Zealand.

The group was to “report and make recommendations of Government… on any matter arising from the environmental, ecological and social effects of the construction and operation of the Manapouri- Te Anau electric power scheme on the townships of Manapouri and Te Anau, the lakes and shorelines of Te Anau and Manapouri, and the rivers flowing in and out of these lakes with particular reference to the effects of lake levels on scenic values, conservation, recreation, tourism and other related activities and amenities”. The guardians were entitled to reports from the Government on actions that had been taken that were deemed relevant so they could fulfil their jobs.

Defining the natural variation of lake levels was considered very important. The lake had already experienced slumping due to a lowered lake level. Also the forest that surrounded the lake was reliant on a variation of water levels. Shoreline beech forest extended almost 3m below the highest natural lake level. The roots of this forest could be submerged for a maximum of 50 days meaning that lake levels needed to be maintained within a range that did not exceed this maximum. The raising of the lake levels too high also had the potential to submerge low lying islands, many of which contained natural vegetation unharmed by red deer.

Lake management guidelines were devised from geomorphological and ecological studies correlated with a 37 year lake level record. The concepts of High, Main and Low Operating Ranges were developed as a basis for management guidelines. The guidelines were verified in practice and incorporated into legislation in 1981. In 1987 the groundings for the Resource Management Act 1991 were being laid. The Government decided that all empowering legislation for hydro-electric stations should be re-issued. For Lake Manapouri this meant a public process was established whereby a working party was formed to examine and resolve a wide range of environmental issues. Lake management guidelines and shoreline monitoring was formalised under resource consents. Also included in the consents was the creation of regulation patterns through the Te Anau and Manapouri control structures to follow more closely to the natural fluctuations of the Waiau River. The resource consent set up legislation which could restore biological and recreational values to the lower river, particularly the section immediately below the dam. Compensation was also granted for a range of adverse environmental effects associated with the diverting of water through the power station.

The Guardians of the Lake were given legal status in the 1990 amendment to the Conservation Act 1987 with additional and similar responsibility for Lake Monowai. The guardians are still active in 2012 and working alongside Meridian Energy, the current owner of the Lake Manapouri Power station.