Saline tidal wetlands are important sites of carbon sequestration and produce negligible methane (CH4) emissions due to regular inundation with sulfate-rich seawater. Yet, widespread management of coastal hydrology has restricted vast areas of coastal wetlands to tidal exchange. These ecosystems often undergo impoundment and freshening, which in turn cause vegetation shifts like invasion by Phragmites, that affect ecosystem carbon balance. Understanding controls of carbon exchange in these understudied ecosystems is critical for informing climate consequences of blue carbon restoration and/or management interventions. Here we present measurements of net ecosystem exchange of carbon dioxide (CO2) and methane, along with ancillary meteorological data, collected from coastal wetlands across Cape Cod to evaluate the effect of hydrological management and salinity on carbon exchange in coastal wetlands.