Given the low passage rates of adult Pacific lamprey (Entosphenus tridentatus) at Columbia River dams, monitoring their migration behaviors at these dams is critical for identifying areas of difficult passage. From 2011-2012, we used Dual-Frequency Identification Sonar (DIDSON) acoustic imaging to observe lamprey passage behavior in fishway environments as part of efforts to identify sites and structural configurations that could be improved to increase lamprey attraction, passage, and collection at dams. For 2012, we used DIDSON to monitor an entrance way to a fish ladder and a junction pool within the fishway at Bonneville dam. Our goals were to characterize the vertical and lateral distribution of adult lamprey, the associations between lamprey and sturgeon activity, and the behavior of fish as they approached and entered the fishway entrance. In addition to monitoring the two locations at Bonneville dam, we also evaluated lamprey passage and behavior at four locations within a fishway at John Day dam. Specific goals for the John Day monitoring were to qualitatively evaluate behavior in relation to a recently installed bollard field, quantify the vertical, lateral, and longitudinal distribution of lamprey, and to qualitatively assess behavior at the transition pool. Results from this study will help evaluate behavior and success at recent fishway modifications, provide insight on potential underlying mechanisms responsible for passage failures, and guide the design of future fishway modifications to improve lamprey passage.