Numerical modeling was performed to analyze the impacts of potential multiphase conditions on long-term subsurface pressure evolution in subsurface systems. An example site on the Bruce Peninsula in Southern Ontario, Canada was selected due to the large amount of available, high-quality data showing significantly underpressured water and the possible presence of gas phase methane. The system was represented by a 1-D model in which multiphase flow and hydromechanical coupling during the last glacial loading and unloading cycle were simulated. Single-phase flow simulations were performed with the USGS single-phase flow simulator SUTRA, and then both single- and multiphase simulations were performed with the multiphase simulator iTOUGH2-EOS7C (herein simply "TOUGH") from Lawrence Berkeley National Laboratory. This model archive data release contains all the input and output files for the simulations and is intended to accompany an article in the Journal of Geophysical Research: Solid Earth (https://doi.org/10.1029/2021JB023322). Descriptions of the data in each subdirectory are given to facilitate understanding of this model archive. File descriptions are provided for select files to provide additional information for understanding this model archive. Support is provided for correcting errors in the data release and clarification of the modeling conducted by the U.S. Geological Survey. Users are encouraged to review the complete journal article (https://doi.org/10.1029/2021JB023322) to understand the purpose, documentation report construction, and limitations of this model.