The Otago Regional Council is keeping a close eye on lake and river levels tonight, after issuing a flood alert for Lake Wakatipu and Lake Wanaka this morning.
Heavy rain expected in the headwaters of Lake Wakatipu catchment over the next few days may see water levels rise enough to cause some surface flooding.
The Otago Regional Council said this morning Lake Wakatipu had risen more than a metre since mid-April due to a succession of heavy rain events in the catchment's headwaters.
While the additional rainfall over the next few days is likely to result in further lake level rises, low-lying parts of the lakeside communities of Glenorchy, Queenstown and Kingston are unlikely to be affected based on current forecasts and modelling.
Lake Wanaka is expected to rise to around 279.2m. Surface flooding is possible there at 280m. It was at 278.6m at 6pm.
The potential for minor flooding of low-lying areas around Queenstown occurs once the lake reaches 311.3m. The lake had reached 310.6m by 6pm.
The Clutha River at Balclutha had also reached its first flood alert level at 6.10pm.
ORC hazards, engineering and science director Dr Gavin Palmer said based on current predictions flooding of Queenstown and Wanaka from the lakes was not a high risk.
However, rainfall predicted for the next 12 hours would push the lakes' levels up to near surface flooding levels.
Dr Palmer said there was some uncertainty around the impact on lake levels of localised thunderstorms, and urged people in low-lying areas to be prepared.
The lakes are expected to be high from tonight or early tomorrow and remain high for the rest of the week.
These lakes had a history of flooding, so taking steps now to ensure mitigation measures were ready was appropriate, Dr Palmer said.
Lake Wakatipu last caused some concern in May 2010, when levels reached 311.48m above sea level, causing some localised flooding through the stormwater system.
