An official with Rockyview County says 13,000 litres of gasoline spilled into nearby wetlands after the accident on the Queen Elizabeth II Highway.
The truck-trailer unit rolled into the median ditch after jack-knifing on the highway not far from Cross Iron Mills shopping centre.
The highway was closed in both directions, backing up traffic, but several lanes reopened after several hours.
No one was injured.
Alberta Environment and crews from the Alberta Emergency Management Agency are monitoring.
“Unfortunately, there was a culvert in the area that allowed the fuel to drain into nearby wetlands,” Grant Kaiser, spokesman for the county, said Tuesday.