Continued low flood risk in Hamilton, Ngāruawāhia, Huntly and Lake Waikare

A fileshot of water flowing from the Karapiro Dam into the Waikato River near Cambridge.  The regional council works with Mercury Energy to manage river flows.

Tom Lee / Stuff

A fileshot of water flowing from the Karapiro Dam into the Waikato River near Cambridge. The regional council works with Mercury Energy to manage river flows.

Waikato River levels are expected to remain high for another 10 days and the risk of flooding remains, the regional council warns.

It said on Friday that low-level flooding in lower areas of Hamilton, Ngāruawāhia and Huntly could still occur, and farms around Lake Waikare could also be affected.

The municipality is working with hydrodam operator Mercury to bring the situation under control, including by controlling flows from a swollen lake at Taup.

State-owned electricity distributor Transpower announced a full state of emergency Friday morning after a failure in a cable carrying electricity from the South Island to the North Island.

Although this emergency call was quickly withdrawn, it highlighted the risks to the power supply at a very cold time of year.

But a Mercury spokesman said in a statement Friday that the situations in the Taupō and Waikato rivers did not limit the generation of the dams.

“Current conditions will not affect Mercury’s ability to generate hydroelectricity on the Waikato River.”

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Waikato Regional Council says flood risk persists in low-lying areas of Hamilton, Huntly, Ngāruawāhia and around Lake Waikare (file).

Christel Yardley/Stuff

Waikato Regional Council says flood risk persists in low-lying areas of Hamilton, Huntly, Ngāruawāhia and around Lake Waikare (file).

The municipality’s regional flood coordinator, Cliff Gibson, said in a statement that Mercury controls flows from Lake Taup and past the dams in Waikato’s hydropower system, while the municipality administers a flood control plan for the lower river.

The City and Mercury are operating under a high flow management plan required as part of Mercury’s resource clearance.

“We are currently in phase 1 of 3 of that management plan, with regular communication between the two organizations and managing the system as much as possible in the circumstances.”

Friday’s latest update from the council’s activated flood control chamber said the Waikato region has seen significant rainfall in the winter and early spring, with Taupō recording the highest rainfall ever recorded.

“Other parts of the region have also reached near-record rainfalls.”

But “on the plus side, we’ve seen a drop in levels in both the Lake Taupō and Waikato River watersheds in the past 24 hours, and we’re likely to get more reprieve over the next 10 days as weather forecasts show favorable weather conditions for the most of the region”.

However, in order to control water levels in the river’s basin, levels will remain higher for at least another 10 days.

“River flow/levels will remain higher than normal, and you can see low-level flooding in low-lying areas of Hamilton, Ngāruawāhia and Huntly,” the council said.

A file shot of Lake Waikare's control gate in February of this year.

Stephen Ward / Stuff

A file shot of Lake Waikare’s control gate in February of this year.

It also noted that the Lake Waikare control gate will remain closed until the river level in the Waikato River recedes, which could affect some farms.

“The level of the lake is expected to continue to rise, and this could mean that low-lying farmland around the lake will be flooded.”

The municipality said local and regional flood control teams were well aware of the management of such events and would continue to monitor the situation closely.

“Our regional flood management infrastructure has risen to the challenge and we are confident it will continue to do so.”