ST. IGNACE, MI - As a security precaution, the U.S. Coast Guard will close the Straits of Mackinac near the Mackinac Bridge to all recreational boat traffic on Monday during the annual Labor Day Bridge Walk.

The temporary security zone will include all waters on either side of the bridge, within a quarter mile of the landmark.

The zone will be in place from 6 a.m. Monday until the event ends.

This extra layer of security follows the decision by the Mackinac Bridge Authority to close the bridge to all regular vehicle traffic on that day from 6:30 a.m. to noon.

Lengthy traffic backups are expected on both sides of the bridge during that time.

"As part of enhanced security measures for this year's event, all waters within the security zone will be closed to recreational vessel traffic," the Coast Guard said in a statement Thursday. "Only commercial vessels with a valid Coast Guard Certificate of Inspection or foreign equivalent, and under the command of a licensed mariner, will be permitted to transit through the security zone."

Freighters, cargo ships or other commercial vessels need to get the Coast Guard's permission to enter the zone, and should obtain it at least an hour in advance. These boats are asked to contact the Vessel Traffic Services St. Mary's River on VHF channel 12.

Any boats that are allowed into the zone by the Coast Guard must not exceed 12 knots. They also may be subject to additional security screening.

Local, state and federal officials will be on hand to enforce the security zone.

"When hailed or signaled by an official patrol vessel, a vessel in the zone is required to immediately comply with the directions given," the Coast Guard said. "Uncooperative mariners will be expelled from the zone, cited for failure to comply, or both."