The objectives of this project are to document the performance and whole-life costs of Best Management Practices (BMPs) and Sustainable Urban Drainage Systems (SUDS). These two terms refer to stormwater practices implemented in the U.S. and UK to reduce the impact of urbanization. The study was undertaken for a number of reasons, including: The lack of data on operational performance (in connection with both water quantity and quality management)A need to better understand future financial liabilities associated with the widespread adoption of these facilities The need to improve confidence in BMPs/SUDS techniques to facilitate appropriate regulation and adoption. The BMPs/SUDS selected for evaluation in this study include retention ponds, extended detention basins, vegetated swales, bioretention, porous pavements, and various infiltration practices. A whole-life cost model was developed in a spreadsheet framework to allow calculation of the expected cost of a facility based on drainage area, maintenance expectations, and other factors. Separate models were developed for five of the selected systems. The default values for many model parameters were extracted from the information gained in the survey of systems in the U.S. and UK.