Your local GIS maps are generally for tax purposes and can be WAY off if not compiled from recent surveys. Mine was off by 5 acres till corrected by survey. Neighbor happened to see the old tax map and claimed my portion. That map was just a sketch that followed and existing cross-fence on our property. He was certain (suddenly) that it was his, although I had been using it for over 40 years, and he only came to his property for 1 week every other year to hunt deer. Original descriptions were from the 1800's which were on his plat that put the lies where they belonged .... as was known all along.

https://maconcountygis.integritygis.com/H5/Index.html?viewer=maconcounty
See what you boundary looks like on the county map.
example:

You need to have a lawyer issue a cease and desist letter to the person who is having the excavation work done, just because you and your neighbor are in disagreement about the lines doesn't make it a property dispute until legal action is taken. I assume you spoke to your neighbor about holding off until the questioned boundary could be settled and they were not agreeable to it. Next you need to hire a surveyor immediately to establish the exact lines as called for in your deed, if your area is like ours, it may be a year or more before a surveyor can get to your job because of the shortage of surveyors, this may well resolve the dispute without further action taken, if it doesn't you will have to have it for court anyway. As you are learning the hard way title insurance is often not very helpful in these types of disputes. As you are learning there is often a lot of overlap in old deeds because of surveying methods used or lack thereof and deeds were just laid out on a handshake as to what the corners were and what the boundaries were. I hope this works out well for you!

Good luck

Dang WT, hate to hear you’re having problems. You’re doing the right thing by going to see a lawyer. Hope things work out for you.

I agree with you crowfoot, that existing “ ancient “ fences are hard to overcome. Missouri fence law and “ adverse possession are another part of it. He made no improvement’s to the 180 foot since he lived there for 40 years. A house was built and improvements made on the 70 some feet on my side of the fence. How does the previous owner of the ground borrow money to build a house on said ground, with out having clear title to it. Isn’t that what title insurance is for?
If I would have got a survey done, would it of showed any thing different than what his shows? My deed plainly states starting and ending point is the quarter section line. Section line’s run in straight lines completely through the entire county. And as I said before, nowhere in my deed are the words used MORE OR LESS. Don’t know if that word age is used in his abstract deed.
Crowfoot I did go to assesser’s office and get copies of the like maps you posted. He explained to me that they are aireial overlays and don’t necessarily show exact dimensions. I asked him to measure their overlay of my ground while I was standing there. It showed 9 acres but they have been taxing me for 12 like my deed shows.

Assessors maps are just for tax figures, but are updated here when an accurate survey is turned in to the county mapper. Still just for taxes tho.
Surveys can get deep. They can go WAY back.
5 neighbors border us. Had to search all of those, of course, plus some beyond them. 2 of which had moved their marker pipes. 1 because he built his cabin too close to the line. (there, fixed it.)

Financing ? many possibilities there. To codes ? also a can of worms.
Good luck my friend, looks good for ya (at a glance)

I can tell you at that point I would likely be in jail. The machine would not be functional if it hit my line. Weather it was the machine or the operator. Something would be broken

You are going to have to hire your own surveyor. But, I’ll bet his surveyor if he’s licensed and legit is pretty close to being on the line.
And as far as proving adverse possession, very tough to prove and very costly.

Assuming that the surveyor who did the work for your neighbor did not make an error and your surveyor finds that the deeds overlap, it will all go back to the senior deed, in this part of the Country (KY) it will often go all the way back to a land grant patten deed from the time of the Revolutionary War. Also it is important to know if the surveyor was hired to do a registered survey or to just run the lines of the property the difference is that in a registered survey the surveyor will establish the validity of the calls in the deed before doing the survey if they were just hired to run the lines they just establish the lines as called for in the deed they were given. This is what often results in these conflicts because the deed they were given doesn't reflect a tract that was severed from that tract at some point in the past in a land transaction and there is a superseding deed to the one that they presented to the surveyor this often occurs when a deed is found to a tract in a person's papers and effects when their estate is being cleaned out and the heirs don't check at the Courthouse for more current deeds.

But at any rate, it is a situation that has to be resolved, as far as the previous owner borrowing money, just like the title company you dealt with the bank took their deed at face value. When was the survey done to establish the previous owners deed? If the surveyor finds that your deed is offset, in other words you own the amount of property that you thought that you owned but the boundaries are just not where you thought they are that is also a bit problem for you as well.

Just be thankful that you are in a part of the Country that uses the township and range method of surveying, as opposed to the meets and bounds method as the township and range method uses unchanging markers for the survey as opposed to going by a certain diameter oak tree to another certain diameter hickory tree at a given bearing and distance. Also if you haven't already done so, I would recommend that you go to the courthouse and get a copy of the neighbors deed and any registered surveys that apply to either deed. You are probably in for a long drawn out and expensive battle if the error is not obvious on the survey or when the deeds are compared. Hope this goes well for you, it sounds like all the neighbor has to lose or gain is a few acres whereas your home is at risk.

Better take video or pictures of all the trees, shrubs, fences etc...before he destroys what could be critical evidence.
And take a couple of measurements to the trees from a corner of your house

Seems to me WT's solution begins and ends with finding EXACT location of quarter section line, the location of which may have to come from geological survey in Rolla. A section is supposed to be 1 mile square. A quarter section 1/2 mile square. Not all are. The exact distance comes from geological survey for his particular section.

I have seen a number of cases where fence lines and thus property lines have been established for generations, yet a new survey comes along and moves the points. The claim is the original property lines were established in error. New points is where it should have been all along. I have also asked real estate experts, lawyers and title company people what the correct resolution is and have never gotten a straight answer from any of them. The most common answer is the new survey puts it right, it is what it is and both sides need to get happy with it. Only one ever does.

And have also come to believe title insurance is a borderline scam........not sure what they do exactly. One thing they all claim is they do not insure property boundaries.

Update after I met with lawyer. I probably can’t win in court (10% chance) trying to beat the ancient fence law on the books in Missouri. Both parties assumed the fence was the line, and it will probably revert to the old fence. On a brighter note it would seem the title company has a real problem on its hands. They should have caught the overlap on the 2 properties before they issued title insurance. They apperantly just rubber stamped it and said service complete and pay me.
Meanwhile back on the north 40 , the neighbor dug a new ditch on his side of the fence and rerouted a spring fed creek so it does not flow anymore over onto my side of the fence like it use to natcheraly. That spring is on his side of existing fence by 10 feet or so, but after 20 yards transfers to my side of the fence. From there it flows into a berried holding tank until full, then overflow’s back into its natural ditch and down to the river. I have installed pump, pump house, hydrants, and irrigation lines so as to be able to irrigate my pecan trees. That set up has been working good for the last 7 years. Now I have no more water and the trees will suffer.
I’m telling you that you can’t make this sh**# up.

Didn't think was legal to reroute a creek .

I don’t know for sure on that drifter, but I’m inclined to agree with you. Rest assured I will find out.

Corp of engineers can tel you I bet.

Things will be better when we don’t own any property. lol

Maybe I ought to run down and have a talk with this neighbor. I don't take kindly to folks messing with my pecan supply.

Hope this all turns out well for ya.

Whoever is in charge of the water in your neck of the woods will absolutely frown on any rerouting of live streams.

Oh my, it sounds like you are in for quite the battle, now you will need to have your property surveyed to figure out what you actually own and that may impact some of your other neighbors, hopefully you will not have to move your house. Hope things go well for you!