But any final decision will be made in the halls of power in Wellington
A meeting in Invercargill yesterday between the Guardians of Lake Manapouri, Lake Te Anau and Lake Monowai and Meridian Energy discussed the lowering of lake levels to increase lake storage, which would lead to the increased ability to produce power.
Meridian Energy wanted the lakes lowered so it could store more water to be used when power supplies were tight, to allow more security of supply.
But its suggestion to lower the minimum level by 20cm was knocked back by the Guardians. The power company also wanted the level lowered an additional 56cm for security of supply during a power crisis.
That suggestion was also declined by the Guardians.
Guardians chairman Darryl Sycamore said the environmental effects were too large for the group to allow.
They did agree to some changes.
The Guardians agreed to drop the restrictions around the equinoctial period in the low-level range of the lakes.
In the four months around the equinox period in both the spring and autumn periods, the levels were not allowed to drop an additional 24cm due to high winds disturbing mussels in the lakes. But the Guardians had dropped that equinox period, allowing Meridian to drop the level all year round, although there were limits on how often.
The upper band of the lower level also had a band of between 201.5m and 201.3m, which was allowed for 88 days of the year.
The 88-day restriction was lifted.
Meridian Energy would also be able to draw down the lakes at a faster rate.
The company had commissioned aquatic ecology and geomorphology experts Mark James, Anne Maree Schwarz and Martin Single to review the impacts of those options.
Meridian Energy statutory advocacy and compliance strategy manager Andrew Feierabend said a compliance buffer of 20cm below the extreme minimum for Lake Te Anau could be used if it was infrequent for short periods such as five days, and cautiously — such as once in a decade.
"The reviews suggest that in the case of a national security-of-supply situation a 20cm extension for generation purposes could be accommodated.
"The nature of the drawdown and duration would need to be carefully managed and controlled."
Mr Sycamore said the evidence presented by the company showed the risk was acceptable and effects on the environment would be no more than minor.
He said the Guardians had to be mindful of the pressure on the electricity system, but its job was to look after the environment around the lakes.
He was mindful people would be critical of the decisions made by the Guardians. The lakes were relatively shallow, so any level change would affect the lakes.
A Meridian Energy spokesman said the government had been clear in its desire to ensure there was enough electricity this winter for all New Zealand homes and businesses, and Manapouri power station had an important role to play in that.
“Meridian believes access to additional hydro storage is essential for security of supply. While around 60% of New Zealand’s electricity comes from hydro generation, only 23% of that capacity can be stored in lakes. Meridian’s lake storage equates to only 15 weeks of average generation."
The Guardians and Meridian Energy would write to the Minister of Energy Simon Watts outlining the decision.
