The Iowa Aquatic Gap Analysis Project (IAGAP) began in 2001 to identify areas in the state where fish species richness lacked adequate protection under existing land ownership and management regimes. Another ma in goal of the project was to create fish prediction data for Iowa streams and rivers. To accomplish these goals, the Iowa GAP team prepared an assortment of datasets that led to the creation of three main datasets: Iowa streams and rivers; Iowa fish habitat models for 157 species; Iowa land stewardship (ownership and management). When the project began, there were few statewide datasets available that provided the type of data needed for this project. Conse quently, much effort was devoted to building the previously mentioned key data layers at a sufficiently fine scale and resolution for subsequent analysis. The exception to this statement was land stewardship; it had been created for the terrestrial GAP project. It need ed minimal editing to serve as a dataset for IAGAP. At the completion of the project, these data became freely available, with the intent that they will be used by those responsible for managing the state’s valuable natural resources, and by the public, so that everyone can be better informed. With this in mind, we emphasize that these data are dyna mic, and in some places, already out of date. Nonetheless, the data and analyses which constitute IAGAP represent an important first step toward understanding the status of fish biodiversity and conservation in Iowa.