Nitrogen‐Loads to Streams: Importance of Bypass Flow and Nitrate Removal Processes

N-loads from subsurface, drains, and groundwater-fed surface (bypass) flows via two riparian zones (crop field wetland) to a second order stream were investigated by sampling of shallow deep groundwater on both sides monthly measurements bypass springs, including water quality (nitrate). A push-pull test in the crop gave first-order denitrification rate (0.23 day–1). Reactive transport modeling evaluated observations chemistry processes below showing that nitrate was completely removed with pyrite aquifer (model rates 0.6–2.5 mmol NO3 L−1 yr−1). drain routed ∼10% regional inflow stream. Buffer efficiency high at 90%. The wetland other side hosts several locations nitrate-rich flow predominantly through non-maintained drainage system drainpipes ditches accounting for 59% input. Nitrate dissolved organic matter groundwater. N load is amongst highest recorded data shows very high. buffer ranged 45% 83% depending if all contributed or only visible outflow. conceptual model removal as function Damköhler number percent proposed.