Reliable collections of science-based environmental information are vital for many groups of users and for a number of purposes. For example, electric utility companies predict demand during heat waves, structural engineers design buildings to withstand hurricanes and earthquakes, water managers monitor each winter's snow pack, and farmers plant and harvest crops based on daily weather predictions. Understanding the impact of human activities on climate, water, ecosystems, and species diversity, and assessing how natural systems may respond in the future are becoming increasingly important for public policy decisions. Environmental information systems gather factual information, transform it into information products, and distribute the products to users. Typical uses of the information require long-term consistency; hence the operation of the information system requires a long-term commitment from an institution, agency, or corporation. The need to keep costs down provides a strong motivation for creating multipurpose information systems that satisfy scientific, commercial and operational requirements, rather than systems that address narrow objectives. This report focuses on such shared systems.