Paper presented at the Sixth Water Information Summit: Breaking The Barriers Let Water Information Flow! Waterweb Consortium and IRC International Water and Sanitation Centre September 9-12 Delft, The Netherlands 2003. Describes the aims, development and functions of the Integrated Information System of the FREPLATA Project and the creation of the Rio de la Plata and its Maritime Front Portal, a cooperative Internet gateway to environmental and spatial information on the Rio de Plata region. The FREPLATA project is a cooperative activity of 18 institutions in Argentina and Uruguay. The Project and institutions with suitably trained personnel designed, developed and implemented databases, applications and standards which enable the systematization of information and constitute tools for management and decision-making.