Last weekend may have been Oamaru’s wettest since daily rainfall records began in 1950, but the deluge that hit eastern coastal parts of the South Island all but missed the southern hydro lakes, which remain at critically low levels for the time of year.
The managers of the southern catchments, Meridian Energy, Contact Energy and Genesis Energy, all reported either little or no additional rainfall.
However, national grid operator Transpower said lake levels now sit at 62% of the national average level for this time of year, compared with 58% before the weekend.
A Meridian Energy spokeswoman said the weekend weather “did not bring inflows to our catchments” above the Waitaki River hydro system and in Lake Manapouri in Fiordland.
However, a small amount of rain had fallen Monday in Lakes Te Anau and Manapouri.
Genesis Energy said its southern lake storage was at 51% of average levels for this time of year and less than a third full.
Further south, the catchment fed by Lakes Wakatipu, Hawea, Roxburgh and the storage Lake Dunstan, Contact Energy reported “a short increase of additional water flowing into one of tributary rivers of Lake Roxburgh, where the Roxburgh dam generates electricity.
But that did not result in any significant or prolonged increase in the Clutha River as a whole.
“As at today, storage levels in Lake Hawea are at 11% of mean, or 7% of full”, and just above minimum operating levels.
A Meridian spokeswoman said also that there was a below average annual winter build-up of snow in the Southern Alps this year.
The National Institute for Water and Atmospheric Research, Niwa, said Oamaru’s 161.2mm of rain last Friday was the most recorded in 24 hours in 67 years of record-keeping. NZN