To evaluate potential impacts of anthropogenic and climatic changes on Lake Melville, a large fjard estuary that receives runoff from the Churchill River in central Labrador, modern sedimentological processes, sources, and distribution of sediment and particulate organic carbon (POC) were investigated in recently deposited sediment (i.e., last 100-150 yrs.). This investigation showed that the Churchill River is the dominate source of sediment and terrestrial POC to the Lake Melville system which could double in the first two years following the proposed hydroelectric development on the Lower Churchill River. The sources, sinks, and losses of particulates and development of sediment and terrestrial and marine POC budgets established in this study can be used to assess changes to the system from future hydroelectric development or climatic changes.