Not even river flow measuring equipment could withstand the weather in south Otago last night with equipment overwhelmed by the rains and struck by lightning.
Roads were also closed as rivers flooded to 10-year flood levels.
The upper Pomahaka River in south Otago, north of Gore, reached a 10-year floodpeak near midnight, reaching an estimated flow of 500 cubic metres per second (cumecs), closing State Highway 90 between Gore and Tapanui.
The Otago Regional Council (ORC) flow recorder site at Leithen Glen, upstream from Tapanui, appeared to have been struck by lightening, meaning council staff had to measure flood peaks on site.
ORC flood manager Chris Arbuckle said 34mm of rain was recorded in 30 minutes.
"Stock losses have been reported in the Heriot Burn and Kelso area. Farmers reported local streams flash flooding, washing over roads and paddocks within 15 minutes of the downpours."
Mr Arbuckle said the Waitahuna River reached an estimated 20-year flood level of greater than 59 cumecs.
"It appears the Otago Regional Council flow recorder was inundated at this flow and communication with it was then lost."
The MetService is predicting more thunder and rain for the region today.
Farmers are reported to be facing a big cleanup in the region.
Heriot chief fire officer Murray Young told National Radio the damage was substantial.
"There's fences down, there's roads washed out, there's dead stock lying all over the road. We've never ever seen anything like this in our lives," he said.
"The depth of water that went down through the golf course would have to be at least 2m and it just came thorough in a wall. It all happened between about 10-15 minutes."
