Benchmark Data

CCD-benchmarks-20230424(XLSX, 129KB)
updated April 2023

Notes: City and County of Denver Benchmark Conversion project--NGVD 29 to NAVD 88:

1. 1. Elevations stamped on USGS BM's (or any BM) should not be used; NAVD 88 elevations should be obtained from CCD database. (Elevations stamped on caps are usually not correct since adjustments to USGS and USC&GS bench lines were published in 1961; Denver adjustments vary from 0.1’ to 0.9’ from the 1961 adjustments).
2. NGVD 29 elevations are no longer supported or published by the City and County of Denver. All elevations refer to the NAVD 88 datum.
3. Conversions were performed by tying existing benchmark loops to NGS benchmarks at either end of the loop and adjusting. NAVD 88 is a non-linear adjustment, so differences between NGVD 29 and NAVD 88 elevations at either end of the line are not constant; this difference must by apportioned throughout the length of the level loop.
   Information on NGS benchmarks is available on the NGS website: www.ngs.noaa.gov 
4. Information about the conversion process itself is available from Paul.Rogalla@denvergov.org
5. While every effort has been made to insure the accuracy of this data, identification and notification of any errors or discrepancies would be appreciated. This information is supplied as information only. This information is for you to use at your own risk and this information may change without notice; no warranty is expressed, intended or implied.

Benchmark data can also be downloaded in different formats from Denver’s Open Data Catalog at denvergov.org/opendata