With floodwaters expected to peak in the northwestern regional hub of Mildura mid-next week, Victorian State Emergency Service deputy chief Alistair Drayton urged people to be safe around rivers.

"It is an incredibly dangerous environment that rivers are moving so swiftly," Mr Drayton told AAP.

"Even for experienced swimmers, there'll be snags and rips in the river and the river's not even within its own footprint at the moment.

The Murray River is expected to peak about 400mm higher than its current level, and would remain elevated for some time.

"This will be with us for many many weeks to come," Mr Drayton said, adding that flooding on this scale was last seen in Mildura in 1973, and 1956 before that.

Residents in the city's northeast near Nichols Point, Bruces Bend and surrounding areas, were told to evacuate on Thursday and warned on Friday it was not safe to return.

Mr Drayton, who took over as Mildura's incident controller on Friday, said fairer weather had provided a break in calls for assistance, providing time to undertake flood mitigation.

"By close of business today, we anticipate all the identified levee works that were being required ... will be being complete, which is which is terrific," he said.

Levee maintenance checks had been showing some sandbags had been going missing in a number of towns along the border.

"It's quite simply a process of going around and maintaining all of those levees and doing some observations because what we have experienced in other places ... sandbags do go disappearing," Mr Drayton said.

More than 500 roads across Victoria remain closed.

With floodwaters from NSW and Victoria beginning to make their way into South Australia, Mr Drayton said tri-weekly teleconferencing between Victoria and NSW's SES would begin to include the SASES from next week.

Australian Associated Press