This dataset is part of the three-dimensional (3-D) hydrostratigraphic model of the Sylvan Lake sub-basin in the Edmonton-Calgary Corridor, central Alberta. It represents the structure top of hydrostratigraphic unit (HSU) S1, which contains coarse-grained material lying directly on bedrock and constrained to paleovalleys in the Neogene-Quaternary succession of the Sylvan Lake sub-basin. This dataset supplements Alberta Geological Survey (AGS) Open File Report 2014-10, which includes a full description of steps taken to produce the structure grid.