National Flood Insurance Program Vertical Benchmarks Maintained by Thurston County Public Works

Thurston County Public Works (TCPW) maintains a network of vertical benchmarks for use by the general public in construction projects as well as for complying with elements of the National Flood Insurance Program (NFIP). Information regarding these monuments can be found on the Thurston County Geodata website at

In further support the NFIP, TCPW annually makes an attempt to recover National Geodetic Survey (NGS) monuments that are of first order accuracy, with stability ratings of A or B, and located within 1 mile of Special Flood Hazard Areas (SFHA) that are identified on the Federal Emergency Management Agency (FEMA) Flood Insurance Rate Maps (FIRMs). Information for the recovered monuments are shown in the table below. Also shown is information on Continuously Operating Reference Stations (CORS) that have been established within 30 miles of Thurston County. Elevation measurements obtained through the use of Global Positioning System (GPS) equipment are acceptable for use in the NFIP provided that at least 3 CORS stations, each within a 30-mile radius of the operator, are used.

The map linked below shows all the SFHAs in the county, the locations of the NGS monuments that are within one mile of any SFHA, and the SFHAs within 30 miles of at least 3 CORS stations. For additional information, please call the TCPW Survey Office at (360) 867-2377.

Map of NGC and CORS monuments
Table of select monuments