In support of the USGS LandCarbon project, field observations of stream and lake carbon gas fluxes and other water-quality data were collected from surface waters in the conterminous US. The sampling was designed to cover a variety of geographic, climatic, and environmental settings to better understand the ranges and distributions of carbon gas fluxes from surface waters. Field observations of carbon gas concentration and flux were paired with laboratory measurements of stream chemical characteristics. Locations were derived from field GPS values or from listed coordinates of USGS streamgages located at the sampling site. Discharge data was either measured in the field at the time of sample collection or downloaded from streamgage data (waterdata.usgs.gov/nwis). Laboratory values were analyzed in the USGS office located in Boulder, CO. The missing values occur in the database for several field observations. Missing values occurred when the site was not appropriate for that parameter (i.e. stream discharge in a lake or reservoir) or due to equipment malfunction.