Update Tuesday 2pm: A VicRoads spokesman said speed limits were returned to normal on the Western Highway through Lawloit at 11am.
Monday 11pm: The Department of Transport says the speed limit on the Western Highway through Lawloit will drop on Tuesday morning, after a salvage operation was completed.
A spokesman said all lanes had reopened, after an earlier operation to recover a bogged truck concluded.
"There is a significant amount of mud and clay on the road surface following the recovery," he said.
"Specialised cleaning equipment has been arranged for Tuesday morning, and temporary speed restrictions will be in place. It's expected to be completed by mid-morning."
The truck ran off the road on Sunday night.
Monday 6.50pm: Police expect one lane of the Western Highway to remain closed through Lawloit for up to two hours, as the operation to remove a truck that ran off the road continues.
Sergeant Darren Wright said VicRoads was on site managing traffic.
"Police are requesting drivers use a slow speed to approach the incident site - to approach at 40 kilometres an hour - and be guided by traffic control," he said.
Earlier: Police expect the Western Highway to fully reopen through Lawloit before 7pm, as a salvage operation continues.
Sergeant Darren Wright said a B double was travelling eastbound near communication towers on Sunday night, when it went off the road and slid into a grass drain.
He said traffic control was in place and police had closed one lane of the highway.
"We are undertaking heavy haulage at the moment," he said.
"We aren't sure what caused the incident but the driver is uninjured. There has been some damage to the truck but none to the road surface.
"We've had one lane closed with traffic control in place for a bit over an hour and at this stage we expect it to open again in the next half an hour to an hour."
Sergeant Wright said the matter was being investigated by Nhill police.
The incident came at the end of Victoria Police's latest statewide road safety operation, Operation Argus, which ran from Friday until Sunday.
Horsham Highway Patrol Sergeant Dale McIvor said the Wimmera division was happy with the results overall.
"There were no serious or fatal injuries, and we were pleased with the crowd behaviour at Pimpinio during the footy finals," he said.
"We also had no significant issues with speeders or any other untoward driver behaviour."
While you're with us, you can now receive updates straight to your inbox twice weekly from the Wimmera Mail-Times. To make sure you're up-to-date with all the news from across the Wimmera, sign up below.