Travel on Highway 63 to Fort McMurray has resumed, but with only one lane open that is alternating between north and southbound traffic.
Flooding has left roads in poor condition and travel is slow going, say RCMP who are discouraging any unnecessary travel.
Flooding had closed the main highway to the oilsands centre in northeast Alberta, as well as alternative route Highway 881.
A bridge on 881, north of Anzac, Alta., was in danger of being washed out, police said. It has now reopened for lighter vehicles.
Cars and light trucks were told to use the secondary highway after Highway 63 was shut down last night south of Fort McMurray.
Provincial officials have issued a high water level alert for parts of Wood Buffalo.
Some residents in the area have voluntarily evacuated their homes.
People are advised to avoid rivers, valleys and low-lying areas.