Water levels peaked at Maitland at about 3.45pm on Monday at 8.17 metres, well below moderate flood levels of 8.9 metres.

By 5.30pm, the water showed signs of receding and had dropped back to 8.15 metres, remaining steady at that level for a number of hours.

The Hunter river peaked at 12.7 metres in the township about 7.30am Sunday, below the minor level.

Superintendent Graeme Craig of the NSW State Emergency Service Northern Zone Hunter Command said it was unclear how long it would take for the floodwaters to recede.

"We're sitting with a catchment that is completely soft and has been for quite some time so any rain that falls goes into overland flow because there's very little opportunity for the ground to soak it up," he said.

"It's a typical feature of a period of La Nina which we are in now."

Superintendent Craig said he had welcomed the assistance of partner agencies since the flood event began on Thursday and which forced the rescue of people and prompted more than 150 calls for assistance across the Hunter and Central Coast on Friday.

They included police, the Rural Fire Service, NSW Fire and Rescue, Surf Lifesaving volunteers, and St John Ambulance.

They have helped move livestock to higher ground including including a cow stranded in Port Stephens on Monday.

"We've had eleven 11 flood rescues from Thursday night, and mainly on Friday, resulting from people drivng into flood water."

"I can't stress enough the danger those people are putting themselves in simply by taking a risk and driving through flood waters - any one of those could have lead to someone dying."

He also warned people, particularly children and teenagers, to keep out of the flood waters, not only due to the immediate risk of being washed away.

"The toxicity of the water they're swimming in - it has flowed over the top of overflowing septic tanks and farmland, so there is the imminent hazard of drowning and also the disease they can pick up from being in that water," he said. "We go into flood water only when we have to and then decontaminate thoroughly."