4.20A Locating and Marking in Navigable Waterways

Facility Owner

A: Permanent Markers for Underwater Facilities12 

Practice Statement:

Permanent markers are placed as close as practical at the entrance and exit points of facilities located underneath bodies of water where facilities are at risk of being damaged. For natural (and other) gas and hazardous liquids pipelines, these affected bodies of waters are “commercially navigable waterways” that have been defined in 49 CFR 195.450 for hazardous liquids pipelines as “waterways where a substantial likelihood of commercial navigation exists.”

Practice Description:

Markers are used by underwater facility owners (e.g., cable, telecommunication, electric, water, sewer, and oil/gas pipelines, etc.) to indicate the presence of an underwater facility in the area. There are many excavating activities (e.g., dredging, bridge construction, anchors, directional boring, and other activities) that can damage these underwater facilities. The proper placement and maintenance of visible permanent markers raise the awareness of these facilities and reduce the likelihood of damage. Markers for underwater facilities follow local, state, and federal laws and regulations. Facility type, name, and contact number of the facility operator are included on markers for all facility types. In some cases, the facility contact is the one call center. Markers include the words “Do Not Anchor or Dredge” and/or applicable warning language.


  • By alerting excavators to the presence of underwater facilities, permanent shoreline markers provide additional protection to the excavators, facilities, and the public.


  • Tennessee Gas: 1995 Procedures, OPS: 49 CFR 192.707, Sunshine State One Call of Florida, State of California Code, State of Delaware Code, State of Alabama Code, State of Mississippi Code


One Call Center One Call Center

Facility Owner Facility Owner

Excavator Excavator

Locator Locator

Project Owner Project Owner

Designer Designer