Paleo-water depth is an important component of modeling surface temperatures through time. Paleo-water depth values represent the elevation of the sediment-water interface relative to global mean sea level at a particular point in geologic time. In most of the model time steps, paleo-water depth values were treated uniformly (single value) across the modeled area of interest, as a simplifying assumption. Most of the model layers were deposited in marine conditions, where the sediment-water interface was below mean sea level (positive paleo-water depths); however, the ground surface of the Williston Basin is now several thousand feet above sea-level, and the Cenozoic model layers were likely deposited in continental conditions, where the sediment-water interface represents paleo-topography (negative paleo-water depths). The model uses the present-day topography to interpolate paleo-water depth between the present-day topography and the uniform paleo-water depth at the 70 Ma time step in the model. The interpolation was generated at three time steps: 50, 43, and 20 Ma time steps, where each of these interpolations is describe with an ASCII grid of map-varying values of paleo-water depth. This is a child item of a larger data release titled "Data release for the 3D petroleum systems model of the Williston Basin, USA".