South Australian authorities were evacuating the small Adelaide Hills town of Echunga on Wednesday morning, and warned a dam burst could be imminent.
The South Australian State Emergency Service issued a dam failure emergency warning after the privately owned dam showed signs of structural failure to its wall.
Due to the “high risk” of the wall collapsing, the SES have warned those whose homes are in danger of flooding to relocate outside the warning area or to the Echunga Football Club.
David O’Shannessy, a spokesperson for the SA SES, said that the Echunga dam’s wall had been compromised due to a combination of conditions from recent wet weather, with the dam full and the ground sodden. He said there were 60 properties in the warning area.
Kylie Simpson, a senior constable with South Australian police, told ABC Radio 15 to 20 homes were in a high-risk situation.
The SES estimated the dam has a capacity of 10 megalitres (about the size of four Olympic swimming pools) and is located less than 500m upstream of the town. Authorities were working to spill water from the dam to lower levels, but there were concerns a dam burst could overwhelm Echunga’s drainage systems.
O’Shannessy said the owner of the private dam had been very proactive and cooperative as the water was pumped out in the controlled release.
Tina Jones, the owner of the Echunga General Store, was woken up at a quarter to six on Wednesday morning by the SES knocking on her door, telling her to evacuate. Jones said the whole town is now “dead … everyone has been packing their cars and leaving”.
She said she was concerned for her own businesses which were directly “in the line of fire”.
SES district officer, Craig Bressington, said crews had been pumping the water in addition to an excavator who had put in a channel for a spillway to reduce water flow in the dam, which was at capacity.
Pumping overnight reduced the level of the dam by half a metre but the spokesperson said that it would need to be reduced by at least a metre and a half “to make it a safe area.”
“Worst case scenario is the main wall of the dam gives way, allowing the water to come down into the town … looking at 30-40 properties could be possibly be inundated with water,” Bressington said.
He said there were currently three medium size pumps operating and that authorities were trying to get another larger pump into the location but are constrained by difficulties access the steep site.
“We’re trying to get another larger pump – that’s a trailer-mounted pump – but, as you can imagine, it’s down in a valley and there’s no roads down to it so we’re speaking to the council at the moment to see how we can get it down there.”
He said it would take another 24 hours for the dam to reach a safe level, but another pump would reduce the time down to 18, possibly 12 hours.
Not all residents in the warning area have evacuated, Bressington said, and that SES members would conduct another doorknock in the afternoon to make sure people had left their homes.
“We just don’t want them to be there in case it does collapse and then that’s going to be a bigger issue for us,” Bressington said.
Police have blocked roads going into the town, which is approximately 40km south-east of Adelaide.
The Rev Matthew Carratt, the minister at Echunga Uniting Church, told ABC Radio Adelaide that “it’s a small community and this is an unexpected event to put our town on the map.” Church members are preparing meals to provide support to those in the evacuation centre at the Echunga Football Club.
One of the employees at the general store, Loma Sillsbury, told ABC Radio Adelaide that the mood in the town was “pretty sombre”.
“A lot of people are very worried, a little panicked,” Sillsbury said. “Everyone is very worried. It is a very big dam.”