Agricultural streams are subject to considerable disturbance including channelization, erosion, and sedimentation. Fertilizer is often applied to agricultural fields in excess of crop demand, and nitrogen (N) and phosphorus (P) can be transported to streams. When contaminated water reaches nutrient-sensitive aquatic areas, excess N and P cause eutrophication and often result in algal blooms, anoxia, and fish kills. Stream restoration has been performed to improve channel structure but also aims to improve multiple stream functions, including water quality. Through this research, I sought to characterize the impact of restoration on N removal via denitrification. Denitrification is a desirable removal process for N in aquatic ecosystems because it transforms a biologically active form of N (NO3-) into gaseous forms (N2O and N2) which are returned to the atmosphere. Denitrification enzyme activity (DEA) was measured seasonally in riparian soil and floodplain and stream sediment in agricultural restored and unrestored stream reaches using the acetylene block method. Across all sites, DEA was significantly higher in floodplain and riparian zones than in-stream (p < 0.001) and dormant season DEA was significantly higher than growing season DEA (p < 0.001). These results highlight the importance of soil texture in stream sediments and percent moisture and organic carbon in riparian and floodplain areas in controlling DEA. It also illustrates the importance of stream-floodplain connectivity and riparian buffers in improving water quality.