SES media officer Bruce Farquharson said 10 homes in Casterton may have been impacted by the floodwaters.

Mr Farquharson said residents of a house in Racecourse Road which was evacuated about 1.30am were later able to access the property by boat to retrieve some items on Sunday.

He said more rain was expected on Tuesday and Wednesday and the Incident Control Centre would remain up and running for the rest of the week. 

An incident control centre was also set up in Warrnambool on Saturday to monitor rising waters in the Merri River and Moyne River catchments.  

The rising waters threatened properties at Rosebrook, Kirkstall and Warrnambool, closing roads including Bromfield Street and Queens Road.

Warrnambool SES controller Giorgio Palmeri said that by late Saturday the water levels in the Merri River had started to drop.

Port Fairy SES unit controller Steve McDowell said sandbags and pumps were used to save a Kirkstall house from floodwaters on Friday night. 

A house at Rosebrook was sandbagged as a precaution on Saturday as waters came within six-feet of the house.

He said there was a lot of water in paddocks around the region that was expected to make its way into the Moyne River or Shaw River near Yambuk.

Mr Farquharson also warned motorists not to ignore road closure signs, with some roads washed away or significantly damaged.

Community meetings will also be held in the Casterton town hall at 5.30pm on Monday, and Coleraine Mechanics Hall at 7.30pm.

UPDATE Sunday 10.30am: Floodwaters inundated Casterton on Saturday night, forcing a household to evacuate.

The Glenelg River at Casterton reached major flood levels overnight on Saturday and into Sunday, rising from 5.63 metres at 6.30pm to 6.10 metres about 4am.

State Emergency Service media officer Bruce Farquharson said the water level had barely dropped since it's overnight peak.

"It's been hanging on pretty well, it's only dropped two centimetres since then," he said on Sunday morning.

Mr Farquharson said two residents of a house in Racecourse Road had to be relocated about 1.30am.

"They took a cautious approach and got out," he said. "They're in alternative accommodation now and are safe and sound."

He said about 45 Casterton residents attended a community meeting held on Saturday afternoon. 

"The Casterton community knows floods, they've had many floods over the years," Mr Farquharson said.

Glenelg Inn publican Troy Robbins said floodwaters came within metres of the hotel.

"It peaked here about 3.45am out the front of the pub, so we didn't have any water inside," he said.

Meanwhile SES Dartmoor members came to the aid of a milk tanker that became trapped in quickly rising water early on Sunday.

SES Dartmoor controller Dallas Oakley said the driver had to be rescued by boat. 

"He decided to drive through floodwater and got stuck," he said.

It took about half-an-hour to rescue the tanker just outside Casterton.

The Bureau of Meteorology issued a major flood warning for the Glenelg River on Saturday night.

Twelve properties were expected to flood, while Murray and McPherson streets were predicted to flood to more than half a metre.

The SES has advised Casterton residents not to walk, ride or drive through the floodwater, keep children away and to stay well clear of waterways, stormwater drains and fallen power lines.

Sandbagging was under way and a community relief centre set up at the Casterton town hall on Saturday.

SES south-west media officer Bruce Farquharson said Casterton residents were warned on Friday night about the impending flood, but none had chosen to leave their homes so far.

Residents at Coleraine were evacuated on Friday night, with tiger snakes seen swimming through the streets to escape the rising water.

Casterton Racing Club's meeting scheduled for Sunday has been cancelled.

The Glenelg River last flooded Casterton in 1996.

UPDATE Saturday 9.30pm: Glenelg Inn publican Troy Robbins expects to have the Glenelg River at major flood level and lapping at the door of his Casterton hotel early on Sunday morning but isn’t too worried.

The State Emergency Service is predicting the Glenelg River will tonight reach the height of its 1996 flood level which only came to hotel’s door so Mr Robbins is not expecting to have water in the hotel’s bistro.

He has sandbags at the ready outside the hotel but hasn’t placed them across the pub’s doors because he doesn’t want them them to get in the way of customers.

With little rain falling in the town on Saturday after it received nearly 50 millimetres on Thursday and Friday, the gently rising floodwaters are attracting a steady stream of sightseers.

The Glenelg River is expected to rise to six metres early Sunday morning, a higher level than it reached on Friday night .

The river is steadily rising again with floodwaters that have come rushing down the Wannon River that meets the Glenelg just south of the town.

On Friday it was engorged with floodwaters from its Bryan Creek tributary that inundated Coleraine, flooding eight houses and eight businesses in and around Coleraine’s main street.

Bryan Creek burst its banks after more than 70 millimetres of rain fell in its catchment area around Melville Forest overnight on Thursday. 

State Emergency Service south-west media officer Bruce Farquharson said Casterton residents had been warned about Friday night’s and tonight’s flooding but none chose to leave their homes.

In a town that has had 12 floods since 1893, residents are familiar with the Glenelg breaking its banks and have developed a lot of resilience about property going underwater.

So far no houses have been inundated in Casterton but the SES has a sandbag collection point by the river for residents and business owners to protect their properties.

Long time Casterton resident Allan Upton said Saturday night’s flood will be a long way below that of the 1946 flood that came in through a window of Mr Robbins’s hotel.

He said tonight’s flood might force a small number of evacuations but he doesn’t expect it to be much worst that Friday night. 

Government agencies told a community meeting in the Casterton town hall on Saturday afternoon that Saturday night’s flooding would isolate some properties.

Incident controller Leanne Simpson said emergency agencies were contacting properties identified in flood modelling as being at risk and the modelling was so far proving accurate.

Police said the Casterton-Naracoorte Road was closed at the southern end between Hanson Road and Casterton and at the southern end of Dergholm.

Warrock Road was also closed at Warrock.

The Casterton jumps races are still expected to proceed on Sunday.

EARLIER: Casterton is bracing itself for major flooding on Saturday night as floodwaters rush along the Wannon River to its confluence with already flooded Glenelg River near the town.

State Emergency Service south-west media officer Bruce Farquharson said Casterton residents were warned on Friday night about the coming flood but none had chosen to leave their homes so far.

Mr Farquharson said the Glenelg River was expected to rise to six metres in the middle of Saturday night, threatening many low-lying areas of the town such as the Glenelg Inn hotel on the Glenelg River and sportsgrounds.

He said sandbagging was underway and a community meeting will be held at 2.30pm this afternoon in the Casterton town hall to inform people of emergency arrangements.

A relief centre will open at the Casterton town hall at midday.

Floodwaters that inundated Coleraine on Friday went on to hit Casterton on Friday night with the Glenelg peaking at 5.86 metres and coming to within four metres of the riverside Glenelg Inn.

No properties in Casterton have yet been flooded but some are expected to go under water on Saturday night.

Prue Robbins from the Glenelg Inn said the concern was that floodwaters presently coming down the Wannon River from the Grampians would hit the Glenelg River on Saturday night at the junction near the town and back up into the town.

She said the rising floodwaters on Friday night had added excitement to the hotel’s trade but no sandbags had yet been laid outside the hotel on Saturday morning.

Warrnambool SES unit controller Giorgio Palmeri said six SES volunteers from the Warrnambool unit went to Casterton to help with sandbagging on Saturday.

Mr Palmeri said Warrnambool SES volunteers had also helped with rescuing people from homes at Coleraine on Friday.

More than 20 properties in and around Coleraine’s main street were flooded on Friday when the Bryan Creek overflowed after about 100 millimetres fell overnight on Thursday in its catchment area in the Melville Forest area.

Mr Farqhuarson said one lane of the Glenelg Highway at Coleraine was now open after the floodwaters closed the highway on Friday.

He warned motorists to take care driving because the heavy rains and floods had damaged many roads.

In Warrnambool, the heavy rains overnight on Friday put floodwaters from Russells Creek across Queens and Bromfield roads but no properties were flooded.