The significant rain forecast means Lake Taupō and Waikato River levels could reach record highs, according to Mercury Energy, which manages the Waikato Hydro System, including dams in the catchment.

Work's underway to move the water through the river system and avoid flooding but high water levels had already impacted some properties, and caused concern, Mercury Energy portfolio manager Phil Gibson says.

'With the ground already saturated from months of rain, there is potential for flooding and raised water levels in the Waikato River and its tributaries.

'Our team are working hard to prepare for next week. We're moving as much water as we can out of the lake and through the river system, using the Taupō Control Gates and eight hydropower dams in the Waikato Hydro System,” says Phil.

Mercury is also lowering the level of the hydro lakes behind mid-river dams to help reduce flooding downstream of Karāpiro.

'We are working with Waikato Regional Council as flood manager on an all-of-river approach to manage the flood ... but there's only so much we can do with the amount of water entering the system,” says Phil.

Properties near the banks of Lake Taupō and other waterways might again be at risk from high water levels over the coming week.

Phil says varying water levels could lead to downstream impacts on low-lying land including some pathways and the Grantham St carpark in Hamilton.

Meanwhile, Tropical Cyclone Gabrielle has forced the postponement of major roadworks on State Highway 1 between Taupō and Tūrangi which were scheduled to start on Tuesday, February 14.

It's disruptive but also the most pragmatic decision given rain forecast for Monday and Tuesday, Waka Kotahi Waikato system manager Cara Lauder says.

The work will see the road closed between 9am and 2.30pm for two weeks.

Stop/go traffic management would operate between the hours of 7am and 9am, and again from 2:30pm until 7pm.

Cara says the team would be unable to start the re-build at Halletts Bay in wet weather.

'We also have a drop-out near a section of road on State Highway 41, between Tokaanu and the turn-off to Omori and Kuratau.

"Currently this is under stop/go traffic management, and we are undertaking work to secure the site ahead of the wild weather," says Cara.

'However, if this area is affected next week, we may not have a suitable detour route, and we will need to reconsider when we can complete the re-build.

'Once this weather event has passed contractors will assess the network for damage, and we will then be able to confirm when we can commence work at sites such as Halletts Bay.”