Utility Locate Marking Colors Explained: Reading the Paint (Oregon)

Quick Verdict

The utility locate marking colors you see sprayed on the ground after an Oregon 811 call follow a national APWA color code, and each color means a different buried line. Red is electric, yellow is gas or oil, orange is communications, blue is potable water, green is sewer or drain, purple is reclaimed water, pink is temporary survey marks, and white marks the area you plan to dig. Reading those marks correctly tells the crew where the dangerous lines are and how careful to be, which is the entire point of calling before you dig.

Why the Colors Exist

Before any trench, the law requires a locate, and you start it by calling 811 (the Oregon Utility Notification Center). Utility owners then send locators who mark their buried lines with paint, flags, or both. The colors are standardized through the APWA (American Public Works Association) uniform color code so that any contractor, anywhere, reads the same marks the same way. For the step-by-step request process, see how the 811 locate process works.

A locate is free and it is not optional. Hitting an unmarked line is dangerous and expensive; hitting a marked one is on the digger.

The APWA Color Code

This is the reference every excavation crew lives by:

The Two Colors That Demand the Most Care

Not all marks carry the same risk, and a good crew adjusts its method by color:

• Yellow (gas) is the line you treat with the most respect. A struck gas line is an immediate explosion and life-safety hazard. Near yellow, crews slow down, hand-dig (potholing) to expose the line, and keep the machine off it. Oregon's propane and gas line trench rules go deeper on this.
• Red (electric) is the other line that can kill. Cutting an energized conductor risks electrocution and arc flash, so red gets the same careful, exposed-by-hand treatment before any machine work near it.

Orange, blue, green, and purple are still expensive and disruptive to hit, but they are not the same life-safety threat, so the response is care and hand-exposure rather than a stop-everything posture.

Reading Flags and Paint After a Locate

Paint goes directly on the ground over the line's path; flags (small colored stakes) mark the same lines where paint will not show, like grass or gravel. A few practical reading tips:

1. Match flag color to paint color. They mean the same utility.
2. Marks show approximate location, not exact depth. The line can be offset a couple of feet and at an unknown depth, which is why you hand-dig to confirm.
3. Look for offset notes. Locators sometimes write an offset distance next to the mark.
4. White is your outline. If you pre-marked your dig in white, the locators marked their lines within and around it.
5. Respect the tolerance zone. Within a set distance on each side of a mark, dig by hand, not machine.

What to Do With the Information

The marks turn an unknown into a plan. Before trenching, the crew walks the marks, identifies which lines cross the work, hand-exposes the critical ones (especially yellow and red), and routes or depths the new trench to avoid them. Skipping this is how utilities get struck. The marks have a limited validity period, so a locate that sits too long has to be refreshed before work resumes. The full trenching workflow lives in our utility trenching guide.

What the Locate Does Not Cover

The 811 system marks public utilities, the lines owned by the gas, power, water, and communications companies up to the meter or service point. It does not mark the private lines you or a previous owner installed on your side of the meter, and that gap surprises a lot of Oregon homeowners. Private lines that 811 will not locate include:

• A buried electrical run from the house to a shop, barn, well pump, or pond aerator.
• A propane line from the tank to the house or to a generator.
• A private water line from a well to the house or to outbuildings.
• Irrigation mainlines, low-voltage lighting, and invisible-fence wire.
• A private septic line or drainfield.

These can be just as dangerous and expensive to hit as a public line, and the responsibility to find them is yours. A good contractor asks about private lines during the site visit, and for property with a lot of buried private infrastructure, a private locating service can be hired to find them. The lesson: a clean public locate does not mean the ground is clear, it means the public lines are marked.

Why Marks Get Refreshed and Respected

Locate marks are temporary by design. Paint wears off, flags get knocked down by mowing or weather, and the underlying validity period expires after a set time. If a project pauses and the marks fade or time out, the locate has to be called again before digging resumes, working off old or partial marks is treated the same as not having a locate at all. On a longer job, crews protect the marks and re-call when needed rather than guessing. This discipline is part of why a licensed crew rarely strikes a line: they treat the locate as a living thing that has to stay current, not a one-time formality at the start of the job.

The Bottom Line

The paint on the ground is a map of buried danger, and red and yellow are the colors that demand the most care. A licensed crew always calls 811, reads the marks, and hand-exposes critical lines before digging. To plan a trench safely, see our excavation services or request a free estimate.