Spatial ETL is a process that extracts, transforms, and loads spatial data between different formats like CAD and GIS. It is necessary because spatial data exists in many formats and converting between them manually is complex and inefficient. Spatial ETL can translate CAD files into a geodatabase, perform geo-referencing, and map CAD entities and annotations to GIS features and attributes. This allows previously inaccessible CAD data to be leveraged in GIS systems. Case studies demonstrate how Spatial ETL helps natural gas and power companies efficiently migrate large volumes of CAD data into GIS for improved access and analysis. Common challenges addressed include changing data representations, connecting networks, and performing quality assurance checks and automated cleanup.