The Laurentian Great Lakes is the world's largest freshwater ecosystem. A charge of the Great Lakes Observing System (GLOS) Regional Association is to help coordinate and integrate data and information relative to the needs of multiple user communities-decision makers with responsibility for coastal resources, maritime operations, human health and water security data, and issues associated with adapting to climate change and weather-related hazards. This article outlines the process GLOS has developed for determining regional data and information needs, how GLOS outreach activities inform data management functions and the development of decision support tools, and how the nearshore network of multiple observation platform types was conceived and is being implemented. The article finishes with a case study of this approach as it is being applied to source water protection, spill response, and search and rescue in the St. Clair River, Lake St. Clair, and Detroit River, the connecting channels that link Lake Huron to Lake Erie.