Traffic on the Welland Canal could come to a halt this weekend.
Unifor members working for the St. Lawrence Seaway Management Corporation have served a strike notice and may walk out at midnight tomorrow.
Unifor says members at seven locals through Ontario and Quebec issued strike mandates.
A release from the union says that "this employer has shown no willingness to address the workers’ concerns in the workplace or approach them with a respectful wage offer"
The 361 employees have been without a contract since the prior one expired on March 31.
A strike now would come as shippers rush cargo through the seaway before the winter closure.