Hydro Storage Remains Below Average

New Zealand’s hydro lake storage remained below average during March 2007, due to a month of mainly below-average inflows.

New Zealand’s hydroelectric lake storage stood at 2822 Gigawatt hours (GWh), 90% of average at the end of March, having started the month at 2970 GWh, 93% of average. The decline followed a month when inflows were below average on 22 days, as much of the country experienced a dry month.

Lake levels were consistently below average throughout the month, hovering between 89% and 96% of average. Storage was considerably below that recorded during 2004 and 2005, but comfortably above the worrying levels of last year, and above storage levels noted during the crisis year of 1992.

However, graphed trends now show that April and May rainfall is now crucial to maintain adequate water reserves for the cooler winter months. If the declining storage trends evident in 1992, 2004 and 2005 apply this year due to a continued dry spell, storage may plunge below that recorded last year. A late reprieve during the latter part of April 2006 (the only year since 2003 to show above average inflows during late autumn) allowed the country to get through without blackouts by careful management of the lakes, increased north-to-south transfers and running of non-hydro plant.

[Compiled from data supplied by M-Co.]

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