Hydro Lake Storage Improves Dramatically

New Zealand’s hydro-electric lake storage levels improved dramatically during October 2007. Lower demand and above average inflows assisted the recovery.

Hydro lake storage stood at 1700 GWh (GigaWatt hours) 75% of average at the beginning of October 2007, but had improved to 2502 GWh (103% of average for the time of year) by month’s end. Storage was generally below last year’s figures but above the 1992 dry year levels until the middle of the month. During the latter part of the month levels improved, and ended the month above levels recorded in 2004, 2005 and 2006.

Daily inflows were at or above average on 20 days, but were erratic throughout the month. Lake levels received big boosts from well-above average inflows on October 1st, 2nd, 17th and 31st.

Daily demand was less than or equal to last year’s figures on 20 days, but peaked at 112.2 GWh on October 3rd, close to last October’s peak of 113 GWh which occurred on October 23rd. The average daily load for October 2007 was 103.1 GWh.

Transfers via the Cook Strait cables returned to a consistent pattern with south-to-north transfers exceeding southbound transfers on all 31 days.

The welcome recovery results from springtime weather which reduced demand, but mainly from several days of good inflows from rain catchments. The storage at the end of the month was better than that recorded for the end of October since 2004, and the return to above average storage reverses the trend set when lake levels plunged to below average in February.

Good snowmelt and another month of spring rains will be required to maintain the lakes at above average levels.

[Compiled from data supplied by M-co.]

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