Alaska Tidal Datum Portal

Unambiguous vertical datums in the coastal environment are critical to the evaluation of natural hazard vulnerability in support of local and regional planning. Appropriate tidal data must be considered in the siting, design, construction, and operations of development projects to ensure protection of human life, property, and the coastal environment.

  • About the Alaska Tidal Datum Portal
  • Frequently Asked Questions (FAQ)
  • Alaska Tidal Datum Calculator

    This conversion calculator is provided as a convenience to facilitate access to vertical measurements that have been independently verified and are freely available from either NOAA CO-OPS or NOAA NGS. For rigorous emergency, planning or construction purposes, users are strongly advised to consult these original sources to ensure accurate and up-to-date transformations. All calculations are based on single tide station offsets, elevations obtained using this method are only valid in the immediate vicinity of the original tide station.

    The values in this conversion calculator were last updated May 2014.

    This conversion calculator is provided as a convenience to facilitate access to vertical measurements that have been independently verified and are freely available from either NOAA CO-OPS or NOAA NGS. For rigorous emergency, planning or construction purposes, users are strongly advised to consult these original sources to ensure accurate and up-to-date transformations. All calculations are based on single tide station offsets; elevations obtained using this method are only valid in the immediate vicinity of the original tide station.

    A summary of relevant information, including links to all of the published values included in this calculator, can be found in the reference table. The table includes all Alaska tide stations with published local datums, however, tidal benchmarks or NAVD88(GEOID12A) tidal benchmark elevations are not available for all locations.

    Conversion between local tidal datums and NGVD29 is not supported by the calculator at this time.

  • Recommended External Resources

The development of this site was partially funded with qualified outer continental shelf oil and gas revenues by the Coastal Impact Assistance Program, Fish & Wildlife Service, and U.S. Department of the Interior. The views and conclusions contained herein are those of the authors and should not be interpreted as representing the opinions or policies of the U.S. government. Mention of trade names or commercial products does not constitute their endorsement by the U.S. government.