Lake Te Anau recommended operating level for this time of year is set to breach unless the flow from the lake is further reduced or the area receives significant rain within the next six days.

The Fiordland hydro lake is currently sitting just above 201.1 metres, its lowest recommended level during the March and April equinoctial period.

Meridian Energy (Meridian) manager Andrew Feierabend said "On current projections, on a no rain forecast, that limit would be reached on the 7th April, which is next Friday."

Feierabend also confirmed the energy generator had made a formal request today (1 April) to Environment Southland to further reduce the flow at the Te Anau Lake Control (TLC) structure.

Environment Southland is currently considering that request.

The Southland App understands the current request may be seeking a minimum rate as low as 50 cubic metres per second (cumecs). This follows an earlier request that was approved just a week ago (25 March) to drop the minimum flow from Lake Te Anau into the upper Waiau River from 115 cubic metres per second (cumecs) to 80 cumecs.

All requests also require consultation and sign-off from the Guardians of the Lakes Manapouri, Monowai and Te Anau, Ngai Tahu and the Fish and Game Council.

Lake Te Anau

Feierabend said reducing the flow at the TLC was the only option Meridian Energy had to manage Te Anau's reducing lake levels.

However, he believed Lake Manapouri's equinoctial limits could be held because of the lake's current inflows and Meridian's ability to reduce generation.

Meridian's Manapouri power station, which has a maximum generating capacity of 19GWh, usually averages around 7GWh at this time of year, but that has now almost halved to just 3.8GWh, Feierabend said.

"If the dry continues we will have to reduce generation even further."

Feierabend stressed that while Meridian's energy generation was very low at the moment, the lights would not going out in Southland.

"There is no issues of security of supply at risk at this stage, because we are managing it in a way that will ensure that people get what they need." 

He said the company had agreements in place and was using other generators to offset any shortfalls.

Meridian Energy communications manager Anna Vrede confirmed they had briefed New Zealand Aluminum Smelters of the current situation.