There is a total of 30,179 groundwater nodes within the C2VSimFG model domain. The model extent conforms to Bulletin 118 boundaries updated in 2003. The grid size was refined in areas of higher groundwater gradient and/or areas that are more critical from a hydrogeologic viewpoint. The average node spacing is 1.5 miles apart and reduces to 0.5 miles along the streams. The grid lines are designed to be parallel to the streamflow direction, when possible, to incorporate the surface drainage patterns. In parallel, the grid lines follow the groundwater streamlines to capture subsurface drainage patterns. Nine major fault systems in the Central Valley are represented by a thin strip of elements.