Nature-based solutions are now commonly used to address societal challenges such as flooding and poor water quality. For example, oyster restoration is applied as a best management practice for mitigating nutrient pollution in Chesapeake Bay and other coastal ecosystems. Unionid mussels, like oysters, can assimilate nutrients through feeding and stimulate sediment denitrification through biodeposition which can remove excess nitrogen. Denitrification is a microbial process that turns reactive nitrogen (e.g. NO3-) into inert nitrogen gas (N2). Enhanced denitrification, mediated by Unionid mussels, can be an important ecosystem service in urban streams where nitrogen is often elevated. In this study, we used benthic chambers to measure the impact of Eastern elliptio (Elliptio complanata) on nutrient and gas fluxes within two restored urban streams in Reston VA. Mussel feeding and biodeposition was also measured in stream-side feeding trays. We found site-specific differences in feeding behaviors (e.g. particle filtration and ingestion rates) likely due to differences in food quality and quantity between streams. At both sites, mussels incubated in chambers with stream sediment increased denitrification relative to control treatments. Benthic nutrient fluxes (e.g. NO3- uptake) were different between streams. The results demonstrate the potential ecosystem effects of including Unionid mussels in urban stream restoration projects as a nature-based solution for nutrient mitigation.