The short answer
811 never marks private irrigation. Before a tree goes in, have the system located: the mainline marked, the heads flagged, the valves found. Most of the time the fix is moving the hole a few feet, which costs nothing on planting day and everything twenty years later.
A tree crew digs the biggest hole your yard will ever see, and they dig it blind. Yesterday's version of that story: a homeowner had a tree planted, the crew cut through the irrigation wires on the way down, and based on where that hole sits, the root ball is almost certainly resting on the mainline. The wires were a few hundred dollars to trace and repair. The mainline is a problem with a twenty year fuse.
What's Actually Under Your Lawn
A sprinkler system is mostly invisible, which is exactly why it gets hit. A typical DFW system puts four things in the path of a planting hole:
The mainline. The always-pressurized pipe feeding the valves. Cut it and the system is down until it is repaired, and a slow crush from a root ball can leak underground for months before anything shows at the surface.
Lateral lines. The zone pipes that feed the heads. Cheaper to fix than a mainline, but there are far more of them, and they criss-cross the yard in patterns nobody remembers ten years after install.
The wire path. Low-voltage wire connecting the controller to every valve. Wire is the thing tree crews cut most often, because it is shallow, it does not spray water when severed, and the crew never knows they did it. You find out weeks later when a zone will not turn on. Our wiring repair page covers how breaks get traced and fixed.
Valve boxes. The access points for the valves themselves. These are the one part of the system that must stay reachable forever, which matters in the next section.
None of this appears when you call 811. That service marks public utilities, gas, water, electric, up to your meter. Everything past the meter is private, including every inch of your irrigation system. The crew that "called it in" did the responsible thing and is still digging blind through your sprinkler system.
The Same Mistake at Three Ages
We work on all three stages of this problem, sometimes in the same week. Here is the progression, from the yard where it just happened to the yard twenty years in.
Year zero: the fresh cut. The homeowner from the top of this page. Tree goes in, wires get severed, and the root ball likely sits on the mainline. The wire repair is routine, trace the break, splice it right, water the tree in. The part that cannot be fixed cheaply is the placement. That tree is not moving, and the mainline under it is now unreachable for the life of the tree.
Year ten: the swallowed access. A customer in Rowlett has two valves sitting underneath what is now a mature tree. The valves still work, for now. But valves are the hardest-working parts in the system, full of diaphragms and solenoids that wear out on their own schedule, and when one of those two needs service there is no way to get to it. The repair that should be an hour in a valve box becomes excavation planning around a tree nobody wants to hurt.
Year twenty: the swallowed valve. Another customer's tree did not just block access, it grew into the valve itself, crushed it, and the valve started leaking. There is no repairing a valve inside a root system. The fix was rerouting that part of the system around the tree entirely, new pipe, new valve location, new wire, a project that runs into the thousands. Our system reroute page describes that work; it is a good page to never need.
The cheap version of this mistake costs a few hundred dollars and shows up immediately. The expensive version costs thousands and bills you in twenty years. Same shovel, same afternoon, same missing ten minutes of planning.
Why It Gets Worse Every Year
Trees and irrigation systems are not neutral neighbors. Roots grow toward moisture, and a buried irrigation line is a moisture machine: every seep at a fitting, every watering cycle, every zone that runs at dawn creates exactly the damp soil profile roots are hunting for. Planting a tree near a line is not planting it near a hazard, it is planting it near an attractant.
That is why "it cleared the pipe when we planted it" means very little. The planting hole is the tree's smallest footprint of its life. Root systems on mature DFW shade trees extend far past the canopy, and species like live oaks are famously aggressive about it; our live oak guide covers just how far those roots travel and what they do to everything in their path.
North Texas clay makes its own contribution. Clay holds moisture unevenly and shrinks and swells with the seasons, so roots concentrate hard wherever water is reliable, and buried lines shift and stress where root mass grows against them. A line a root "found" does not get gently moved aside. It gets pressed, bent, and eventually crushed or cracked, and because it is underground, the first symptom is usually a water bill or a soggy patch months after the damage started.
Before the Tree Crew Arrives
The fix for all of this is sequencing. The irrigation knowledge has to arrive before the shovel does.
Have the system located. A pre-planting locate marks the mainline, flags every head near the work area, and tracks down the valves. Honest scope note: lateral lines cannot be reliably traced, no tool does that well, but the mainline, head, and valve positions tell you where the laterals run, and a lateral nick is the one kind of damage that is genuinely cheap to fix if it happens. The dangerous targets, the mainline, the wire path, the valve boxes, are exactly the things a locate pins down. Details on our valve locating page.
Pick the spot with the flags in view. Most of the time the answer is not "you cannot plant here." It is "move the hole four feet." A planting hole runs two to three times the width of the root ball, so the flag map turns an invisible gamble into a simple placement decision, made while the tree is still on the truck.
Tell the crew what the flags mean. A good tree company will happily hand-dig the last stretch near a marked line. They do not want to cut your system either, they just have no way to know where it is. Give them the map and they become careful exactly where careful matters.
Keep valve boxes clear, forever. Whatever else moves, no tree goes on top of a valve box. That is the one placement that converts a working system into a future excavation project with certainty, it just needs enough years.
Never let a planting hole get dug between your water meter and your valve boxes without knowing where the mainline runs. That corridor is where the highest-consequence pipe in the system lives.
If the Damage Is Already Done
If the tree is already in and something is wrong, the playbook depends on what got hit.
A zone stopped working after planting. That is the classic cut-wire signature. Wire breaks are traced electronically and spliced with waterproof connectors, usually without major digging. Start at our wiring repair page.
Soggy ground, a spinning meter, or a mystery water bill. That points at pipe, and the line leak repair guide walks through how leaks get found and fixed, including under landscaping.
A valve you can no longer reach, or a system that needs to move around a tree. That is reroute territory, planned so the tree stays and the system works around it. The earlier it is caught, the smaller the reroute.
And if the tree is going in next week instead of last year, you are in the cheap chapter of this story. Keep it that way.