THE Mary River is expected to peak at 17 metres this morning.
That is less than the 2013 peak of 19.98m, but it will flood Gympie businesses in the Jaycee Way area of the CBD.
Major flood levels were expected at Dagun Pocket and Gympie overnight and into today.
Rainfall totals of 120-200mm have been recorded over the catchment in the past 24 hours.
Gympie's Local Disaster Management Group met yesterday afternoon to discuss the flooding.
A traffic management system is in place, with no B-doubles entering Gympie.
To the north, they are being kept at Curra, and to the south, the left lane of Mary Valley Rd.
Smaller trucks and all cars are being diverted on to the Mary Valley Link Rd, which is expected to be inundated sometime this evening.
Police and Traffic Management will begin closing the road approximately two hours beforehand to ensure no traffic gets stranded.
Normanby Bridge becomes inundated at about the 15.8m mark, but will be closed before the waters reach that level.
Based on the rate of rise of the Mary River yesterday, the Normanby Bridge was expected to close early last night.
Council's infrastructure services are deploying equipment and staff to the Southside for when the bridge is closed.
The SES has a team set up on Southside, Queensland Fire and Rescue has a swift water rescue team at the pavilion and another at Monkland until roads are reopened.
The Queensland Ambulance Service will have one crew located on Southside. The group, which is scheduled to meet at 8am today, will continue to update the community.
Weather warnings, road closures and other important information can be found on council's website - gympie.qld.gov.au and social media.