The collapse prompted residents to suggest debris caught in scaffolding left on the bridge had contributed to its demise, although a review commissioned by the Dunedin City Council found "no definitive reason" for the collapse.
The conclusion prompted Doug Miller, an East Taieri resident, former weed sprayer and three-term regional councillor, to contact the Otago Daily Times.
He blamed the bridge collapse on a lack of maintenance by the ORC, which had failed to adequately ensure crack-willow was cleared from the banks of the Taieri River.
That meant more debris was able to be washed down the river during last year's flood, contributing to the bridge's collapse.
"It's a man-made fault through a lack of maintenance," he said.
"They [ORC staff] have kept pretty quiet on the thing."
ORC environmental monitoring and operations manager Scott MacLean, responding to ODT questions, would not be drawn on whether inadequate maintenance was to blame for the failure.
Last year's flood had resulted in many rivers carrying "significant debris loads, including vegetation", but it was not known whether that had contributed to the Sutton bridge collapse, he said.
"The ORC has not conducted any investigation into the cause of the damage to the bridge, therefore we are unable to comment on this," he said.
The ORC regularly conducted crack-willow removal along the Taieri River, as well as other sites across Otago, as part of its routine work programme, he said.
However, it was "not feasible nor desirable to remove all trees growing on the margins of rivers", he said.
Dunedin city councillors last week approved a plan to replace the old bridge with a modern structure expected to cost between $1.2million and $1.6million.
The new bridge would use heritage elements where possible, and 76% of the cost was expected to be covered by the NZ Transport Agency.
