It will be another six months before further information on flood mitigation measures for the lower Taieri will be available, Otago Regional Council environmental engineering and natural hazards director Gavin Palmer says.
Mr Palmer was commenting on a report to the engineering and hazards committee which updated councillors on the Taieri flood risk assessment and scheme review begun in 2006.
Four mitigation options had been identified by the review and hydraulic modelling had been undertaken by consultants.
However, while it had shown it was possible to mitigate the flood problems, it would be at the "expense of potentially adverse effects'' elsewhere, he said.
Further investigation of the options was needed over the next few months, especially relating to the Silver Stream, to hopefully come up with one or two preferred options and a clear understanding of their effectiveness, impacts and costs, he said.
"Realistically it will be another six months before we can take this further.''
Also to be determined in coming months was what the appropriate standard of flood protection for the area was, Mr Palmer said.
Cr Gretchen Robertson said any mitigation works could have big consequences and be expensive.
Deputy chairman Stephen Woodhead said the study was a work in progress and before the council did any physical work, proposals would go to the community for consultation to assess what level of risk they were prepared to put up with and how much they would be prepared to pay to manage those risks.
Chief executive Graeme Martin said also to be considered was the need to balance physical works and other possibilities, such as altering existing land use or building prohibition.
These issues also needed to be worked through with the Dunedin City Council, he said.
Cr Shepherd said lay opinion in the district was that removing bed material in the Silver Stream would ease the problem.
Mr Palmer said that had been looked at but removing the bed material did not make a huge difference.
"We've got to do something more comprehensive.''
The committee committed to brief the Dunedin City Council and the Mosgiel Taieri Community Board on the findings so far.
