Projected PLSS vs. real PLSS

[fowledup]

I've noticed that on the latest version of a Ca. BLM map I have that the Section lines have moved as much as 300' in spots from the previous edition. How does this effect claim boundaries? If contested, what would be the standard by which to go by- the most current mapping data, or historical reference from maps available at time of location?

 

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[Underburden]

Who is the cartographer for this BLM map? Should be noted somewhere on the map.
If it's not USGS, then I'd question the authenticity, validity and legality.

 

[Hoser John]

New cadestral surveys move things around quite a bit. Lips and Del Norte can fill ya in much better than I on this subject. As technology improves so lines move. Compare USGS topos from the 60s-70-and on and amazing changes--John

 

[fowledup]

All is legit these are true BLM maps. Yeah, I've been comparing to old topos I've collected over the years definitely some movement. As our technology and mapping gets more and more accurate. How will it effect property boundaries and how will the courts deal with it? Hopefully they L and D will chime in on this. Always something huh?

 

[Clay Diggins]

Not sure if you are writing about a paper map or?

The survey lines didn't change and the projection doesn't really matter as long as they didn't use any of the non standard map projections Google uses (they may have see below).

The lines on a map aren't the official survey even though they come from the BLM. The pins on the ground are what matters and those don't change. The BLM can't just survey an unsurveyed area. It takes an Act of Congress with funding to initiate a new survey and there hasn't been one of those since 2002. The BLM can however resurvey to reset lost or missing pins and make projected grids over unsurveyed lands.

If you are in California a lot of the land there has never had a cadastral survey so the Township, Range and Sections are "projected" by grid as if the land had been surveyed. This has been done poorly in the past in some areas and some projected grids are being replaced. These projected grids over unsurveyed land are theoretical only.

If you located a claim without a real, on the ground, cadastral survey in place you may have relied on a projected survey on a map. I always recommend using metes and bounds descriptions on those claims on unsurveyed lands as well as making a general reference to the projected grid. If you haven't done so you might have some issues with BLM minerals but maintaining your stakes and monuments will give you a leg up over their nonsense. The actual location on the ground legally trumps all the maps and projected surveys. Another reason to clearly mark your location on the ground.

Following the law of location laid down in the 1872 Mining Act is always a good idea. Locators are instructed to use metes and bounds locations when there is no survey. The rule for surveyors prohibits projecting surveys involving property rights that are more than two miles from the nearest physical pin. Beyond that there is no expectation of accuracy.

The BLM has been using a very old PLSS shapefile with a lot of errors and some pretty bad "fixes" for years. They do have the new CadNSDI files that might become the new digital PLSS but those have their own problems. We are investigating those right now but the BLM has been reluctant to share all of those. We are working with them to see if those Cad files will work on our maps. We are also working on making the Survey Field Notes available for download from our maps. A lot goes on behind the scenes to make accurate maps available at Land Matters.

Google projections can not be approved by the standards organizations because they are about 300 feet off and they won't follow any standards. That's fine if you are just using Google Maps or Google Earth and you just want to see what's nearby but measurements are not accurate and other maps won't line up.

If you are using GIS software and using a Google projection like 900973 or 3867 or one of the other 5 or so projections they hop between you will probably need to add "reaspect=false" to your call code - that should move the lines over about 270 feet and get you within 30 feet of the one you are used to. If you don't have to use a Google projection avoid them if you want any accuracy.

That may seem like a lot of information but you asked a pretty complex question. I hope the information helps. If you have more questions feel free to ask. We've got a real life cadastral surveyor here on the TNet prospecting forum and maybe he will add some inside information for you.

Heavy Pans

 

[fowledup]

Excellent info, I apologize for posting the question so broadly, it was sorta intentional. You verified my thinking and provided a ton more useful info as usual, thank you. What I was looking for is further clarification/verification that the new maps are based on and are still "theoretical" projection as well, with no real legal basis, and that a true survey from nearest pin is what trully matters. A recent map observation and subsequent conversation brought up the basis of my original question. We are safe with ours as we do as suggested and do both descriptions for the most protection we can get.
Now a new question surfaces, concerning gps age or gps program age and accuracy when using for placing markers for metes and bounds. Is there a year cut off where things signicantly changed, with equipment or accuracy?

 

[2cmorau]

sweet very good info
pin on the ground i am fimiliar with in AZ, a bearing tree would in affect be just the same correct?
there by giving induviduals some degree of security of A.P. description in locating open ground

 

[Clay Diggins]

Now a new question surfaces, concerning gps age or gps program age and accuracy when using for placing markers for metes and bounds. Is there a year cut off where things signicantly changed, with equipment or accuracy?

In May of 2000 the selective GPS system was dropped and commercial GPS could gain greater accuracy with an updated GPS unit. (commercial GPS is the class of handheld GPS device available to the general public without a license)

• Before May 2000 the accuracy of GPS was 300 foot.
• IF a GPS unit used after May 2000 was capable of using the enhanced system and IF the conditions were right* the new system provides a 10 meter accuracy (30 foot).
• Add in a fully WAAS capable GPS unit (since 2005) with as many as 11 satellites and the right* conditions and accuracy could be as high as 3.5 meters (10 foot).

(*The right conditions are Southern US with clear dry sky, no sunspots, no overhead obstructions and at least three steady satellite connections with 42 seconds of settle time and quality GPS unit)

Seldom do even the best GPS units provide repeatable accuracy in those ranges under real world conditions.

Most recreational GPS users don't understand how to take an accurate reading with a handheld GPS so accuracy varies quite a bit. GPS is constantly improving but "advances" like cell assisted GPS and Google Earth are actually misleading many users to believe accuracy is better than it actually is. Combine these systems and accuracy goes down. Learn to use a dedicated GPS unit properly and accuracy goes way up.

Professional and Military grade GPS is a whole different world. With vastly improved precision professional systems can, in trained hands, provide consistent accuracy of up to 6 cm (2.5 inches). Military? Who knows.

Heavy Pans

 

[Clay Diggins]

sweet very good info
pin on the ground i am fimiliar with in AZ, a bearing tree would in affect be just the same correct?
there by giving induviduals some degree of security of A.P. description in locating open ground

Trees die and are chopped down. They don't qualify as a "permanent monument".

Take a lesson from professional mineral surveyors. Find nearby bedrock that is easily locatable by written description and chisel your mark in it. Describe your beginning corner from there. If there is no bedrock look for a really big boulder not in a stream and do the same. If you can't find a suitable rock then set your own pin and accurately locate it. You can always give a very good written description of a starting point and locate from there.

You aren't restricted to just the corner stakes either. Put in very tall steel pipe stakes and set them in concrete. Done properly they can be rigged with zip and drag lines for mining.

In many areas of the desert claimants have cleared their boundary lines of all rock and brush (clearly marked on the ground). You can still see very good examples of this method in places like Little San Domingo and the Cargo Muchacho Range. These cleared boundaries last 100 years or more in the desert.

Most importantly maintain your claim, don't make anyone guess whether they are on a mineral claim.

Heavy Pans