Southeast Texas Orthometric Heights
NGS Datasheet Impacts in Southeast Texas (NGS’ Response)
In February of 2020, NGS provided surveyors with a list and map of the 28 bench marks in the area with reliable NAVD 88 heights (SE TX Valid Ortho Heights). Warning flags, shown in red on the datasheet to the right, were placed on all datasheets in the area of suspected vertical motion.
In March 2021, all the marks with warning flags (except the 28 marks listed on the SE TX Valid Ortho Heights page) had their heights suppressed. This means that NGS removed the published orthometric height from the positional section at the top of the datasheet and listed those old heights in the superseded section of the datasheet. Until new surveys are completed on these marks and the data is submitted to NGS, only the 28 marks listed on the SE TX Valid Ortho Heights page will be considered to have valid NAVD 88 heights.
In addition, to access the datasheets of suppressed marks using NGS search and download tools, users will be required to acknowledge they are requesting datasheets with suspect heights, as shown here, including requested suspect heights 
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