Problem: Urban watersheds are composed of a complicated spatial fabric and are influenced by a wide range of often competing economic, policy, and public interest drivers and constraints. With increased regulation of stormwater discharges taking place on a national basis, there are greater pressures on municipalities to develop effective urban stormwater management strategies. In addition, highlighted by recent events in Iowa, there is great interest in flooding and potential mechanisms for better managing the landscape, including urban areas, to improve hydrologic response and reduce damaging flooding events. To these ends, there is a great need for effective tools which can aid the design and execution of such strategies by identifying hot-spot areas contributing to excessive discharges and pollutants and to evaluate potential best management practices. Methods: This project will address urban hydrological problems in the first instance and year by developing processes for incorporating Light Detection and Ranging (LiDAR) elevation data into modeling processes using an industry-standard urban watershed model (WinSLAMM). Iowa is one of the first states in the country to have state-wide coverage of LiDAR data and this presents an opportunity to develop improved WinSLAMM modeling processes using LiDAR data. These processes will be initiated in the Dry Run Creek (an impaired waterway) watershed (85% of Cedar Falls) and then transferred to the Catfish Creek watershed which overlaps with large portions of Dubuque. In the event of second year funding, a new ArcGIS extension, called ArcWinSLAMM, will be developed. This extension will provide more efficient mechanisms for input parameterization of WinSLAMM and allow for easier visualization of modeled results. The extension will be developed with standard application development tools and will be made freely available. The development process will include beta testing by personnel with WinSLAMM modeling experience. In addition, training sessions for using the new ArcWinSLAMM extension will be provided at the end of the project. Objectives: The goals of the project include the development and demonstration of more effective WinSLAMM modeling processes utilizing LiDAR topography data in the Dry Run Creek and Catfish Creek watersheds, the development of a freely available ArcGIS extension which will improve efficiency and accuracy in WinSLAMM modeling, and technology transfer in the form of training and provision of the free extension. The project will lead to novel techniques and technologies, adoptable throughout the country, for addressing both water quality and quantity (flooding) issues in urban watersheds.