Environmental problems give rise to some of the most complex problem-solving processes our society faces. In these processes multiple stakeholders represent contested objectives while critical variables can only be estimated, making projections uncertain at best. A complex network of influences, competing objectives and uncertainties can overwhelm the cognitive capacity of even the most sophisticated decision maker. Increasingly, statistically-based computer-implemented decision support systems (DSS) are being introduced to assist stakeholders and decision-makers in coping with these complexities. From local watershed councils to the Environmental Protection Agency, to the Nature Conservancy, organizations are using DSS in a wide range of environmental problem-solving scenarios. The increasing use of DSS tools in environmental decision making raises a number of questions that merit critical study: How are these technical tools influencing the decision-making process and what is the effect on breadth of public participation? When a computer-based decision support system arrives at the table, which stakeholders have their voice in the debate amplified and which have their voice diminished? In which contexts and scenarios do these tools promote equity among the various stakeholders? In which do they reinforce existing power differentials? What is the effect on the distribution of costs and benefits? Do DSS tools promote efficiency and effectiveness in complex multi-stakeholder processes? Although a great deal of technical research has gone into the creation of DSS tools these critical questions remain unanswered and are largely unstudied. This project will use qualitative and quantitative to address these questions by conducting a study of the salmon recovery process taking place in the Columbia River Basin. The answers to the above questions are important. It is widely acknowledged that public participation is crucial to effective and long-lasting solutions to environmental problems and so it is important to understand how the use of tools such as DSS affects collaborative problem-solving. This project not only seeks to understand the effects of DSS tools, but to improve their design and use, leading to more effective and more resilient solutions to today's environmental problems.