Plans to move contentious Vic flood levee

Emergency services in a northern Victorian town are planning to relocate a controversial flood levee that left homes on the wrong side of it inundated.

Residents in flood-ravaged Echuca were furious last month after a decision was made to pump floodwater towards houses on the other side of a levee built through residential streets to save the town centre.

With flood conditions easing at least temporarily, Victoria State Emergency Services Incident Controller Paul Bates said emergency services had been consulting and planned to move the levee further north to contain more houses.

"We have talked to the community and understand the concerns and we are doing some planning work on hopefully being able to move that in the next little while," Mr Bates told AAP.

"But overall, the levee's done a really good job."

Campaspe Shire Council has been contacted for comment, but said at the time the decision was made by Emergency Management Victoria, and that the council was not consulted on the levee's location or design.

The emergency level in Echuca has been downgraded to watch-and-act and it is safe for evacuated residents to return to the town, which sits at the confluence of the Murray and Campaspe rivers.

Mr Bates said while slowly receding floodwaters meant emergency services could start planning a transition from relief response to recovery, forecast thunderstorms towards the end of the weekend were cause for concern.

"The modelling from the Bureau (of Meteorology) suggests that river rises won't be anything to worry about but if you get a heavy thunderstorm the potential for flash flooding ... and winds from thunderstorms can cause issues too particularly with saturated soil and trees," Mr Bates said.

While recovery efforts are ramping up further south in Rochester, Mr Bates said about 50 residents were still in need of temporary accommodation who were being supported at the relief centre.

A severe thunderstorm warning was in place on Thursday afternoon for damaging winds and large hailstones in areas along Victoria's border with South Australia.

Authorities warned of a high risk of thunderstorm asthma in the Mallee and Wimmera regions, while there was a moderate risk in the South West, north central, and central districts, including in Melbourne.

Asthmatics and people at increased risk of thunderstorm asthma, including those with hay fever, should carry reliever medication and avoid being outside during storms, authorities said.

A certain type of thunderstorm and high amounts of pollen in the air can trigger thunderstorm asthma.

The mess left by recent flooding has also created perfect conditions for dangerous mould to thrive, putting asthmatics and those with allergies again at risk, the National Asthma Council said.

"When a mould source is disturbed, small particles called spores are released in the air, which can then trigger asthma and allergy symptoms," spokesman and GP Dr Joel Ten said.

"The symptoms can include nose, eye and skin irritation, sneezing or wheezing, and severe breathing difficulties in some people."

Mr Bates warned residents in flood-affected areas to avoid flood waters, and said long sleeves and repellent should be used to prevent mosquito-borne diseases.