The Otago Regional Council said up to 160mm of rain fell in parts of Dunedin, causing surface flooding and dozens of road closures around the city and the Taieri Plain.
Just after 1pm on Sunday the MetService upgraded its heavy rain warning for coastal Dunedin and Clutha to red, its highest level, warning of a threat to life from dangerous river conditions, significant flooding and slips, disrupted travel and the possibility of communities becoming isolated.
The Dunedin City Council activated its Civil Defence bunker on Sunday afternoon as localised surface flooding was already appearing on roads.
Flood protection barriers were installed in Surrey St and self-serve sandbag stations were opened at the Dunedin Ice Stadium carpark and at Mosgiel Memorial Park.
On Sunday evening Mayor Sophie Barker urged people to stay home and avoid unnecessary travel as surface flooding and minor land instability emerged across the city.
Civil Defence controller Sandy Graham said the rain arrived earlier than expected and the bunker would operate overnight.
Mosgiel residents were asked not to shower or flush toilets while a malfunctioning valve at the wastewater pumping station was repaired
The emergency control centre kept a close watch on Mosgiel as wastewater issues backed up and heavy rain persisted.
About 10pm Ms Graham asked all residents to significantly reduce use of the network, noting the Mosgiel system was one connected network.
Two state highway closures were in place, on SH88 between Station Rd and Borlases Rd and on SH87 from Kyeburn via Middlemarch to Outram.
Rivers that rose during the day in Dunedin held steady, but rainfall was predicted to spike about midnight.
Just before midnight an evacuation centre opened at the Taieri Bowling Club in Mosgiel, after water rose rapidly in High St from 10.30pm following a heavy deluge.
As the MetService indicated rain would peak about 2am, part of Gordon Rd was closed in central Mosgiel to stop water washing into shops.
Tyne St, Reid Ave, Stirling Cres, Ross St, Burling Cres, Tay St and Perth St were closed.
In the early hours of Monday the council urged residents to stay safe as heavy rain persisted.
Three Mile Hill was closed because of surface flooding and small slips were reported on Otago Peninsula. Ms Graham said the stormwater network continued to work within capacity.
As daylight broke crews were able to assess damage and identified hazards.
Incident controller Chris Henderson said significant rain had fallen over the past 24 hours and it was not over yet.
A fallen tree blocked part of Portobello Rd near Bacon St, and no buses were running beyond Broad Bay.
Kaikorai Valley Rd was closed between Townleys Rd and Stone St.
At noon on Monday the council warned swimmers and surfers to stay out of the water for 72 hours and warned shellfish gatherers not to collect and consume any shellfish because wet weather overflows had discharged to the sea via the Lawyers Head outfall and other waterways.
By Monday mid-afternoon the Mosgiel evacuation centre and the emergency control centre had closed as the response moved from emergency to recovery.
Rivers and streams had peaked and water levels were subsiding, although standing water and debris remained in places.
