This project will provide the first ever multi-year dataset of the complete carbon budgetof a tidal marsh, including continuous measurements of atmospheric and hydrologic carbon exchange. This dataset will be used to expand an existing Bay-Delta marsh biogeochemical model that predicts seasonal and annual carbon budgets in tidally-driven marshes over a range of salinity values. Net carbon balance will be measured in two tidal marshes (Rush Ranch in Suisun Marsh and Eden Landing on San Francisco Bay) and the data will be used to develop a modeling tool to predict carbon sequestration, subsidence reversal, and climate resilience of tidal wetlands.