SAULT STE. MARIE, Mich. (AP) — The U.S. Coast Guard is conducting its annual retrieval of buoys from the Great Lakes and the St. Lawrence Seaway.

Operation Fall Retrieve began last month and is expected to be completed by Dec. 28.

The Coast Guard plans to retrieve 1,264 navigational aids, including lighted and unlighted buoys and beacons. The number being pulled out of the water represents about half of the navigational aids the Cleveland-based Ninth Coast Guard District manages in the region.

The purpose of the buoys — of which there are 2,599 in the area — is to mark safe passage for domestic, international, commercial and recreational vessel traffic.

U.S. waters are marked by what is known as the Aids-to-Navigation System, which employs a simple arrangement of colors, shapes, numbers and light characteristics to mark navigable channels, waterways and obstructions adjacent to them.

The buoys are an important part of the system.

They’re being removed because of decreased winter vessel traffic and to minimize damage from ice and severe weather.

Six Coast Guard cutters are involved in the effort.

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