An Aquatic and Riparian Effectiveness Monitoring Plan (AREMP) for the Northwest Forest Plan is intended to characterize the ecological condition of watersheds and aquatic ecosystems. So to determine the effectiveness of the Northwest Forest Plan to meet relevant objectives, this report presents the conceptual foundation of options for use in pilot testing and implementing an effectiveness monitoring program for aquatic and riparian systems. The base program would evaluate status and trends of watershed, stream, and riparian conditions by using decision-support models. Although the focus of AREMP is on characterizing ecosystem status and trend, implementing it will also supply information that will be useful in determining causal relations to help explain those trends.