Blog · September 28, 2026
GPS Elevation Is Not a Topographic Survey
The height on the screen is a rough number.
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Why this comes up
The height on the screen is a rough number. Do not design a drain or a building pad from the GPS elevation.
What to check on the map first
County GIS lines are assessment maps. They are not a survey, and a product will not redraw them.
Open Platbookmapper and choose the state. The directory sends you to the county viewer. Match the parcel ID before you trust a pin on an aerial photo.
A tool that matches the job
Shop the Garmin GPS when that is the job in front of you. Do not design a drain or a building pad from the GPS elevation.
The limit
A handheld GPS gets you back to the truck. It is often several meters off, so it cannot tell you where the legal line is.
Walk the parcel in daylight before you trust a gadget at dusk.
Not a survey. County GIS and tax parcel maps are assessment and planning layers. They are not a substitute for a recorded plat, deed, or licensed survey.