Flood-affected residents in the Northern Territory have been warned not to swim in crocodile-filled waters, as tropical lows continue to bring major flood warnings and heavy rains to the Top End and Queensland.

Hundreds of people were evacuated over the weekend, with the entire town of Nauiyu/Daly River in the NT evacuated as of Sunday afternoon, the NT chief minister, Lia Finocchiaro, said.

The Katherine River level peaked at 19.2 metres at 10.45 pm on Saturday, the highest since floods in 1998 which claimed three lives. The Daly River was still rising on Sunday and expected to exceed 1957 levels – 15.3 metres – during the next week.

The NT incident control acting commander, Shaun Gill, urged residents not to venture into flood waters after reports of people swimming.

“There are crocs absolutely everywhere … please don’t go in the water,” he told a press conference on Sunday morning. “Don’t swim in the water for two reasons. It’s because it’s a fast-flowing river, and also this is when crocs are most active.”

Gill said there were about 1,000 people in shelters after “a very difficult day” of evacuations on Saturday from Nganmarriyanga (formerly known as Palumpa), Nauiyu (the Daly River community), Katherine and Jilkminggan. Six aircraft and 18 helicopters were used in the rescues.

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Finocchiaro said 80 people who were unable to leave on Saturday due to weather conditions had been evacuated that morning after being taken to higher ground by boat during the night.

“They took shelter overnight, and then we’ve been able to helicopter them out this morning,” she said. Federal and territory governments were activating assistance payments for the Katherine local government area, capped at $1,537 per family, alongside a re-establishment assistance fund available for eligible households of up to $8,847.

The Bureau of Meteorology’s Jude Scott said the Daly River could remain at major flood level “for at least this week and into next week”.

“The Daly River is a huge river holding enormous volumes of water, so it will continue to slowly rise during the next week.”

The Katherine River was still at major flood level on Sunday afternoon. Bureau of Meteorology senior meteorologist Angus Hines said the focus was moving to Queensland, where a severe weather warning for heavy rainfall was in place for the state’s north-west on Sunday.

A tropical low was expected to gradually move to the south-east during Sunday, continuing into Monday. Isolated six-hourly rainfall totals of up to 100mm were expected, with totals as high as 170mm on the Sunshine Coast.

Hines said the region was experiencing the cumulative impacts of a “long and quite widespread wet season”.

“There’s been some flood warnings already go out preemptively, ahead of that heaviest rain arriving, with a lot of minor to moderate flooding expected across the south-east of the state,” Hines said.

“If that rain comes to a little heavier, we certainly can’t discount the risk of major flooding as well.”

A flood watch warning was in place for most of Queensland, with major flooding a risk on the Georgina, Lower Flinders and Thomson rivers.

Evacuations and power outages

Finocchiaro said government offices and courts and several schools would not be open on Monday, with some schools being used as shelters. She said two people who had remained at Katherine hospital on Saturday had been evacuated to Darwin. Twenty-one patients were at a temporary emergency department established in the town’s industrial area, while 20 pregnant women had been airlifted to other hospitals as a precaution.

The chief minister said the Stuart Highway remained closed due to flooding on both sides of the town, leaving it isolated and travel dangerous, but said trains would now be moving from Alice Springs to Darwin, which she said was “good news for food”.

Hines said water levels in Katherine had started to drop as rains eased slightly, but said there was a chance more isolated rainfall could “pump more water into the river”.

“We wouldn’t rule out a sort of renewed rise in that water level the next couple of days, but for the time being that water level is starting to drop.”

Asked about reports that residents had been unable to reach emergency services through triple zero, Gill said he did not have details of specific incidents but said the advice remained to call the number, saying there had been about 120 emergency calls. He said there had been “telecommunications issues” alongside power outages affecting at least 90 homes.

One resident posted in a Katherine community Facebook group that she had seen a crocodile floating down the street, while another video posted to social media showed a crocodile galloping across a road in the town on Saturday morning.

The NT government put out a #BeCrocwise message to residents amid this week’s flooding, advising people to stay away from the water’s edge, not to enter flood waters and keep children and pets away.

“With current flooding and rising river levels in the Big Rivers, crocodiles can move into new and unexpected areas, including creeks, drains, flooded roads and other waterways.”

“Assume any waterway may contain a crocodile.”