Technical Abstract: This article introduces a series of papers that report results of field studies to determine the effectiveness of drainage water management (DWM) on conserving drainage water and reducing losses of nitrogen (N) to surface waters. The series is focused on the performance of the DWM (also called controlled drainage [CD]) practice in the US Midwest, where N leached from millions of acres of cropland contributes to surface water quality problems on both local and national sales. Results of these new studies are consistent with those from previous research reported in the literature that DWM can be used to reduce N losses (primarily in the nitrate nitrogen [N03-N] form) from subsurface drained fields. The measured impact varied over a wide range (18% to more than 75% reduction in N loss to surface waters), depending on drainage system design, location, soil, and site conditions. Crop yields were increased by DWM on some sites and not on others, with the year-to-year impacts of DWM on yields dependent on weather conditions, as well as the above factors.