Alexandra Police have released the name of the man missing at the Talla Burn stream near Beaumont in Otago.
He is PAUL WILLIAM WILSON, aged 28, civil engineer of Roxburgh.
A land and water-based search and rescue effort involving around 20 people continues today. It includes land search and rescue staff, the Dunedin swift water rescue team and the Police National Dive Squad, which travelled from Wellington to arrive on site at 1pm today.
The Dunedin swift water rescue team and Police National Dive Squad are searching an area of the stream 400 metres above the Talla Burn's confluence with the Clutha River. Two hundred metres of the stream is steep with a boulder stream bed, while the other 200 metres is slower flowing.
Detective Sergeant Derek Shaw, of Alexandra, who is in charge of the search and rescue efforts, said the river was in flood when Mr Wilson went missing yesterday. It had however dropped considerably overnight, and was returning to normal levels and clarity. This was assisting the search, he said.
About eight people including SAR staff and family members of Mr Wilson were carrying out a land search close to the river. This morning a helicopter also completed a sweep of the locality and a jet boat completed a sweep of the Clutha River downstream from where Mr Wilson went missing. Both were unsuccessful.
There had been fantastic support from the local Miller's Flat community who were providing catering and other assistance, Detective Sergeant Shaw said.
"As time passes naturally our concern for Mr Wilson grows and we have grave fears for his safety," Detective Sergeant Shaw said.
Detective Sergeant Shaw expected that the search would continue until nightfall this evening, when search plans for tomorrow would be re-assessed.