Extended time-series sensor data were collected between 2012 and 2016 in surface water of a tidal salt-marsh creek on Cape Cod, Massachusetts. The objective of this field study was to measure water chemical characteristics and flows, as part of a study to quantify lateral fluxes of dissolved carbon species between the salt marsh and estuary. Data consist of in-situ measurements including: salinity, temperature, pH, dissolved oxygen, redox potential, fluorescent dissolved organic matter, turbidity and chlorophyll. Surface water flow, water level and water elevation data were also measured. The data provided in this release represent a compiled data set consisting of multiple sensor deployments between 2012 and 2016.