SToRM is a component of the USGS Multi-Dimensional Surface Water Modeling System (McDonald and others, 2012). SToRM is one of a generation of recently available 2-D hydrodynamic models available without charge or for low cost. In this paper SToRM was applied to two test situations where actual measurements were available in part to test the tool itself at physical scales that differ by about an order of magnitude, and to develop the skill set necessary to use the tool for an arbitrary situation. The two cases are a 200cm wide, 1400 cm long, 100cm deep laboratory flume with 3-D velocity measuring capability and a field site during a flood event that engaged about 30 meters wide flow between cross sections located 100 meters apart. The flume geometry is far smaller than for which SToRM was intended, however after considerable iteration, the program was able to produce results that compared favorably with measured velocities in the flume. The lesson from flume modeling was that the simulation process is quite iterative. The field case study used SToRM to model a flood event for which the authors had collected actual water surface elevations by conventional post-event survey. The input discharge was estimated by conventional indirect methods. As with the flume simulation, through considerable iteration SToRM eventually produced results that were consistent with observations. The extension of the topographic survey (real data) into an elevation grid suitable for the 2D hydrodynamics software was more complicated than anticipated, and suggestions are provided to help with the diagnosis of a poor elevation grid. The other overall substantial lesson is that convergence in the software has a far different meaning than convergence in the mass-balance sense. These different connotations were not apparent in the documentation, and without an understanding of this particular issue the apparently converged results could greatly mislead the analyst. Examples from our simulations are provided along with a suggested approach for using SToRM.