In mid-July, lake levels were at a near-record low in the South Island.
Now, after persistent rain, they are above the 91-year average for the first time since early May.
The low lake levels had been keeping the country’s hydro operators on edge, but they have been able to breathe a sigh of relief for the first time in a while.
Meridian wholesale general manager Chris Ewers said recent rain had caused Lake Pūkaki to rise by about 2 metres since its lowest point in late August, with a further 80mm-160mm of rain forecast over the coming days.
He said South Island averages had also been boosted by huge inflows into Lakes Manapōuri and Te Anau, and both were now at the top of their ranges, with another 200mm of rain forecast this week.
‘‘Bit by bit, our hydro storage is increasing.
‘‘Pūkaki is still well below average but steadily building, while the rapid rise in Lakes Manapōuri and Te Anau is due to their smaller storage capacity.
‘‘That means we can rely on strong generation out of Manapōuri Power Station while Pūkaki refills.
‘‘Things are continuing to look more positive, but there’s still some way to go.’’
He said snow storage in the Waitaki catchment had increased to 86% of average, up from 83% last week.
Snow melt contributed signficantly to Waitaki catchment inflows over the summer period, he said.
Meridian’s six wind farms also continued to perform well, generating 41GWh over the week.
Strong winds and increased hydro generation meant average wholesale prices (also known as spot prices) of just $19/MWh in North Island and $17/MWh in the South Island, with extended periods of prices sitting just above $0.00/MWh in both islands, he said.
This had been the case for the past three weeks.
Meridian’s wind generation was also set for a further boost thanks to an agreement with Transpower for the loan of a transformer to West Wind Farm.
West Wind has been running around a third below maximum capacity since one of its transformers failed in May 2023.
The temporary replacement would be installed in mid-October, he said.
‘‘Being back to two transformers at West Wind means an extra 44 megawatts of generation potential.
‘‘This winter’s demonstrated the importance of every single megawatt, and we’re very grateful to Transpower for their generosity and flexibility.’’
A permanent replacement was expected to arrive at West Wind Farm in mid-2025.
