Tired of carrying pen and paper in the field, or squinting to read someone else’s handwriting? How about entering pages of data? With over 560 outfalls to monitor, the City of Dayton has evolved its monitoring and illicit discharge detection data collection and management process. This presentation will share lessons learned of the successful transition from the pen and paper of the past to the latest GIS-based mobile application. Some of the topics will include the reasons for a new tool, how the Collector app and dashboard were built, a demonstration of the app, how data is visualized in the dashboard for quick analysis, updates and improvements after three field seasons, and next steps for GIS-based apps. GIS is a great tool to help monitor and track illicit discharges. It eliminates need for paper, keeps data in one location, exporting data is quick and simple, assists in finding outfall locations, aids in tracking down illicit discharges by having the entire MS4 mapped out, and creates a good visual representation of where to focus efforts. We will continue to refine the app and explore other uses for GIS-based mobile tools. In the beginning, it was very important to work closely with GIS team to create a useful tool and then to have regular communication to identify updates or changes needed. We will also outline the recommended tools needed to start your own Collector app (ipad, GIS software, etc). By using these mobile GIS tools Dayton has created an efficient and effective method for meeting and exceeding the permit requirements of monitoring and IDDE.