A MAJOR new flood study for the Condamine River and tributaries through the former Warwick Shire costing $840,000 is expected to prevent building on floodplains for the next 50 years.

The Southern Downs Regional Council's Engineering Committee this week endorsed the calling of tenders for a consultant to complete the study after continued concerns about unauthorised building, particularly in rural areas.

The study will cost ratepayers more than $200,000 this financial year with the remainder of the funding coming from state and federal sources.

As well as updating peak flood predictions for the urban area of Warwick, the study will for the first time establish flood lines for outlying areas on the Condamine for nearly 80 kilometres - from Killarney to Pratten - and along tributaries including Dalrymple, Swan, Emu and Farm Creeks.

Mayor Ron Bellingham agreed it was indeed “a huge amount of money” to have to spend but said the new maximum flood levels the study would set would provide certainty for building purposes well into the future.

“The risk of building on the flood plain continues to be a concern, particularly in the rural areas where we have newer people coming in who perhaps are not as aware of the risks as others,” Cr Bellingham said.

“An earlier study mapped the areas below us, from our boundary out to Dalby some years ago, so it is time to complete the exercise for our own area.”

The mayor confirmed the council had written to at least one property owner in a rural location in recent years advising them they could be at risk from a major flood.

He also acknowledged the current lack of “official” flood levels outside Warwick could potentially expose the council to legal action.

“It is the sort of situation where you would hope common sense would prevail but sadly that is not always the case,” he said.

He said predicted peak floods in Warwick had largely been “proved” by the 1976 flood but some minor alterations could be expected to result from the study.

Tenders for hydrological consultants will be called in the next few months and the study is expected to take at least two years to complete.