TWEED Shire Council has denied its main catchment facility in Clarrie Hall Dam had any impact on the severity of the recent flood.

Several residents, including at last week's SES flood forums, have questioned whether the dam overflow had any impact on the record flood that so devastated parts of the Tweed.

Council's director of engineering David Oxenham said the dam, located near Uki on Doon Doon Creek, which feeds into the Tweed River, was built purely for water catchment and not flood mitigation.

Clarrie Hall Dam is not a flood mitigation dam," Mr Oxenham said.

"There was a suggestion at the (SES) meeting that we could have lowered the dam prior to the rainfall event.

"That is absolute nonsense. The dam is not designed to provide any form of flood mitigation.

"Its size, compared to the catchment, is very small. It has a catchment area of about 60sq km, which is tiny when you think of the catchment upstream of Bray Park weir, which is significantly larger."

Mr Oxenham said if anything the dam would have slowed the torrent of water flowing down the Tweed River but acknowledged the event was unprecedented.

"It is the highest flow event we have ever had at the dam - the amount of water that flowed over the spillway was twice the capacity of the dam," he said.

"The dam is 16,000ML and we had 33,000ML go over the dam in that event over a 24-hour period."

The council has started work on increasing the dam's capacity to 42,300ML for future water needs.