MetService have predicted significant rainfall for the headwaters of the Southern Lakes between 5:00am Monday and 5:00pm Tuesday. They expect 400 to 500mm of rain to accumulate on the main divide with 180mm to 280mm 20km east of the main divide. The most intense period of rain is expected between 6:00am and 2:00pm on Tuesday.

Heavy rainfall would cause river and lake levels to rise in the Wakatipu, Wanaka, and Hawea lakes catchments.

Lake Wakatipu is expected to rise to around between 310.6m (above sea level) and 311.4m, depending on the predicted rainfall scenario. The potential for minor ponding of low-lying areas around Queenstown occurs once the lake reaches 311.30m. Low-lying parts of the lakeside communities of Glenorchy and Kingston could be also be affected.

Lake Wanaka is expected to rise to around between 276.9m and 278.2m depending on the predicted rainfall scenario. Surface flooding is possible there at 280m.

ORC Manager Natural Hazards Jean-Luc Payan said that as these lakes have a history of flooding, it is appropriate to take steps now to ensure mitigation measures are ready.

“We advise people camping or tramping in low-lying areas to take care and be mindful of rising lake and river levels. Boaties should also be wary of floating debris in Lakes Wakatipu, Wanaka and Hawea that may be washed in from swollen tributaries.

“The lakes are expected to be high from early tomorrow and remain high for the rest of the week,” said Mr Payan.

An intense band of rain will also move across Central Otago and the Lower Clutha region (including the Pomahaka catchment) around mid-day tomorrow. Total rainfall of up to 20mm over a 2-hour period may be experienced during this time, which may cause localised flooding.

The heavy rainfall is expected to move quickly north on Tuesday afternoon and no significant rainfall is forecast for the remainder of the week.

ORC staff will continue to monitor the situation and issue further updates and specific warnings as required.

The last time Lake Wakatipu caused some concern was in May 2010 when levels reached 311.48m and caused some localised flooding in Queenstown through the stormwater system.

River level and rainfall information is available on http://water.orc.govt.nz, or by phoning 0800 426 463.