The loss of control marks, also known as “passive marks,” is still a problem today and was discussed at the 2023 CLSA Geomatics Conference at Cal Poly Pomona/College of Engineering.

California surveying agencies played a part in replacing and updating lost marks for the NAVD 88 project and it seems that they are doing it again.

The importance of saving surveying control marks was highlighted at the 2023 CLSa Geomatics Conference at California Poly Pomona/College Of Engineering.