Hydro Lake Storage – Cause for Concern

Hydro Lake Storage during October failed to benefit from hoped-for springtime inflows and ended the month below average for the time of year.

Hydro lake storage at the beginning of October 2006 stood at 91% of average. During the month inflows from snowmelt and spring rains were below average on 24 out of 31 days, and storage at month’s end was only 94% of the average figure, showing little gain for the month.

As the month progressed, daily storage figures were close to last year’s until the 15th when they began to show a steady improvement, an encouraging sign that we are not entering the dry summer with a serious deficit like last year’s which sparked concern over continuity of supply.

However, with the cold snaps continuing to strike the country, it was unusual that the supply of energy from non-hydro sources in the North Island has not been maintained. These north-to-south electricity transfers, which have been a key component of energy supply management during the winter season, virtually ceased during October 2006.

It would appear that energy managers are hoping that the large inflows will be late this year (as they were in 1992 and 2004) but figures for the early part of November show a continued decline.

With a dry summer forecast for many parts of the country, this is a cause for concern for the capacity of North Island hydro storage which usually benefits from winter inflows. The South Island storage lakes usually benefit from inflows during spring time, which is already well-advanced.

[Compiled from data supplied by M-co.]

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