The overarching goal of this project is to understand how the salt marsh ecosystem could be affected by proposed hydrological modifications. To achieve this, we propose to monitor a section of tidal marsh with a sediment observatory in order to characterize the present system. We will then reduce the flow in this stretch of tidal marsh by installing a sill in the tidal channel, which will reduce velocities and create an anoxic zone behind the sill, mimicking eutrophic conditions. The sediment observatory will be used to monitor the changes to the system, in conjunction with assessment of how the microbial community and structure and functioning changes. These results will be extrapolated to demonstrate how the estuary might respond to the proposed modifications and what the implications of these results could be for the management of the system.