BUSINESSES in Murwillumbah are bracing for the impact of flooding with heavy rain expected to push the Tweed River over flood levels.

Murwillumbah District Business Chamber president Toni Zuschke said the river was only 2m away from topping its levy.

And as the Richmond-Tweed State Emergency Service is predicting a flood level of 4.5m about 3pm (NSW) today Ms Zuschke is predicting "we're in trouble".

"We'll be isolated soon," she said. "Half of the shops in town are closed because people can't get to work.

"I haven't seen it like this in a while - half a dozen roads are shut in town.

"In Budd Park, all the chairs people use to sit and look out over the river are underwater.

"Heritage Wharf's roof is just poking through the water."

She said there was water over the road at many of Murwillumbah's access points such as Melaleuca Station, Clothiers Creek, Queensland Rd, Tyalgum Rd, and it was lapping at Byangum Bridge.

"The Farmers Market is cancelled because it's under water, Knox Park is under and Nullum St is closed.

"We've put out a flood warning on our website, and if you don't have your flood plan in place now you're way behind the eight-ball."

Ms Zuschke said Murwillumbah's current flood risk was moderate and she was not aware of any flooded businesses yet.

"That said, the Riverview Hotel looks very close; the river's 1m and a half from their balcony," she said.

"At the moment it's about as high as the floods we had recently, and how bad it gets depends on how much water comes down through these upper reaches.

"It will just back up at hight tide, and disperse."

See the chamber's flood plan at www.murwillumbahchamber.com.au/.