The Lismore-Bangalow Road also was closed as crews from Byron Bay and Mullumbimby Rural Fire Service, Bangalow Fire Brigade and RTA cleaned up the spill.
One of the worst-affected areas was at the Bangalow roundabout.
The 34-year-old Queensland driver of the truck was interviewed by police after he had stopped at Clunes.
He told police he had lost about 280 litres of diesel.
The Environmental Protection Authority is investigating the spill.
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