Cotton Australia says up to half of the cotton around the central Queensland town of Theodore has been wiped out by floodwaters.

Roads in the region remain closed as the swollen Dawson River continues to inundate cotton crops.

Rob Cairns from Cotton Australia says it could take weeks to see the full impact of the flood damage to properties.

"In the Theodore region we've got about three-and-a-half-thousand hectares of cotton planted and early estimates suggest that up to 1,700 hectares has been damaged and some of that will not get harvested

"So up to 50 per cent of the crop has been lost there and certainly in those other areas we'll work with the government departments to assess as the water gets away to really assess the impacts of those crops in those regions."

Mr Cairns says the damage bill is likely to exceed $8 million.

"A big impact on individual growers, a lot of our growers throughout Queensland have come off a number of years of drought and the smaller crop that they did have in the ground was really important for them from a cash flow point of view in getting them to the next season," he said.

"While this water is helpful for future years, the impact on this year's crop is obviously quite devastating."