The International Great Lakes Datum (IGLD) is the vertical datum in which the measurement of water levels, depths and flows throughout the Great Lakes region are meaningfully and consistently related to each other for the management of water resources and flows. The datum is defined and maintained under the auspices of the Coordinating Committee on Great Lakes Basic Hydraulic and Hydrologic Data, a bi-national committee with representatives from the Governments of Canada and the United States. To ensure the vertical datum provides accurate heights, it must be updated every 25-30 years to account for the effects of glacial isostatic adjustment throughout the Great Lakes region. The first IGLD datum was IGLD (1955), which was later updated to IGLD (1985). These datums used dynamic heights and were defined by spirit levelling, an expensive method susceptible to the accumulation of systematic errors. A new IGLD (2020) is presently under development based on the forthcoming NAPGD2022 and will be accessible using modern GNSS technology. This will enable millimeter-level measurements of water levels to support safe navigation, regulation of waters & flows, lake level forecasting, hydroelectric power generation, and many other resource management and development activities. We discuss the four main attributes defining the datum, in addition to the determination of dynamic heights, how heights can be more efficiently and accurately determined with GNSS and the results of the 2022 GNSS survey of Great Lakes water level gauges. We also briefly mention the evaluation and modelling of lake topography (hydraulic correctors).