This ongoing research will help answer the questions that continue to arise as Reclamation is faced with detailed analysis and modifications of spillways and other earth-retaining structures subjected to significant seismic loading. The objective of this research is a better analytical tool to predict the seismic lateral earth pressures for configurations that include groundwater, cohesion, nonhorizontal zone, and compaction/in-place density effects under various ground accelerations. This report represents the conclusion to the first phase (Scoping Phase 1) of this research  project. The ultimate project purpose is to complete a full scale shake table test of a concrete cantilever retaining wall.