The importance of freshwater ecosystems in the terrestrial carbon balance from watersheds to the globe has been increasingly recognized over the last two decades. While global-scale annual carbon exports from rivers to the oceans are reasonably well constrained, large uncertainties remain at other spatial and temporal scales for lateral transport and other fluxes. Measurements are sparse across much of the world, and flux calculations typically involve a mix of disparate observations. Detailed characterizations of fluxes necessarily involve a combination of observations and models of varying complexities, ideally grounded on consistent digital river networks, drainage boundaries, and watershed characteristics derived from spatial datasets. This presentation will illustrate some of the challenges — and missteps — based on recent modeling efforts and data compilations, and discuss paths forward for retaining the provenance of observations and constructing reusable, consistent community resources of observations, model outputs, and spatial frameworks.