Boulder Overboard: When Assumptions About Property Lines Go Wrong

by | Jan 15, 2026 | Property Lines

What happens when a homeowner assumes land is “common ground” and moves a huge boulder across a property line?

In this real-life example, Shelly from Cardinal Surveying & Mapping breaks down a boundary survey completed in 2023 and explains how a simple assumption about a creek, overgrown land, and a distant fence led to a costly misunderstanding.

In this video, you’ll learn:
✔ Why overgrown areas and creeks aren’t automatically common ground
✔ How to read your survey drawings correctly
✔ What happens when property is assumed to be unowned, but isn’t
✔ Why boundary surveys protect both homeowners and neighbors

If the homeowner had reviewed his survey, he would have clearly seen that the land behind his property was privately owned, not municipal or shared space.

Before you move rocks, fences, sheds, or anything else make it know what you own.

📞 Questions about your property or boundary lines?
Call Cardinal Surveying & Mapping at 636-922-1001
📧 Email: inbox@cardinalsurveying.com

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Video Transcript:

Hi, I’m Shelley with Cardinal serving. So I have a little lesson that I’d like for everybody to learn today. So today’s example is a boundary survey that we performed, back in 2023. And I recently got this email from the homeowner who wanted to read this to you. Quick question. Can you easily check even for a fee, if there is a common ground between my property and my neighbors behind me, that back left corner.

My neighbor says his property goes all the way up to my. I pushed a huge boulder out of my back garden with the bobcat and it went past my property line. Stupidly, I assumed there was common ground. His fence is like 50ft away and there is a creek. I don’t see any chance of that being the case. And that 50ft behind his fence is totally overgrown may be a bad assumption, but I figured the creek would be common ground.

I have no problem moving that boulder. If he’s correct. If he’s wrong, and it’s no one’s property, that boulder will stay put. So the question is this gentleman had a boundary survey done. We marked the corners. He’s obviously aware of where his property is, because he even said that he pushed the boulder beyond his property, but he just assumed that that property that was overgrown, that has a creek that is behind him was not actually owned by any one person, but was either common ground or owned by the municipality.

Now, if he had taken the chance to look at the survey drawings that he had been provided, he would see that unfortunately for him, his neighbors right. If you look at this second sheet, here is our lot. We actually have neighboring property owners right next to us. If this area were common ground or if it were owned by a municipality, it would be labeled as such.

So technically, he’s push that boulder onto somebody else’s ground. If you have questions about your property and what you do and don’t own, please call us. Let us help you. You can reach us at 636922 1001, or feel free to send an email to inbox at Cardinal surveying.com. Where Judy and Jasmine Jasmine will promptly return your email. We look forward to working with you and as always, make it known what you own.