The purpose of this report was to collect data and analyze evidence to help determine the extent of navigability on the Cosumnes River; enabling us to more clearly establish sovereign interest. Specifically, this report addresses how much of the river is and was navigable. The determination of the last natural location of the river and public use easements were not included in this study. Although our research was extensive, obviously all sources were not exhausted and further findings may change the conclusions drawn in this report.