British Columbia’s chief veterinarian has issued an order making it illegal to transport boats or other watercraft without removing the drain plug to prevent the spread of whirling disease.

Whirling disease, which is fatal in fish, is caused by a microscopic parasite that mainly targets salmon and trout. The Ministry of Water, Land and Resource Stewardship says the order takes effect on Friday and is also intended to keep invasive mussels out of B.C. waterways.

Boat operators are required to clean, drain and dry all watercraft and remove all mud, sand and plants before leaving the shore.

Vessels will also have to dry out for at least 24 hours before entering new waters.

The ministry says inspectors will be checking watercraft for compliance with the new orders.

Whirling disease causes deformities in fish and has a high mortality rate but poses no health risk to people swimming in or drinking water that contains the parasite responsible for the condition.