Sites selected for ocean energy projects (e.g., wave energy) are typically near estuaries and bays. A wave energy project had been planned in the ocean at depths of 62–69 m near Reedsport, Oregon, northwest of the Umpqua River estuary. Green sturgeon (Acipenser medirostris) from the southern and northern distinct population segments (DPS) use this estuary during the spring–fall, presumably for feeding. The Southern DPS is listed as threatened under the U.S. Endangered Species Act. A “beforeafter” study was designed to identify potential interactions between the proposed wave energy project and green sturgeon, but the project was terminated before fieldwork ended. Nonetheless, understanding movements and habitat use of green sturgeon near estuaries and bays is important for site selection of future ocean energy projects. Using up to 43 automated acoustic receivers within and outside of the proposed project area, we monitored for the occurrence of 770 subadult and adult green sturgeon tagged with coded ultrasonic transmitters, which were affixed by other researchers on unrelated projects. We detected 248 green sturgeon within the receiver array from January 2013 through June 2014. Green sturgeon were detected on 492 of 515 monitoring days (95.5%) by the ocean array of receivers anchored at depths of 12–110 m. Peak detections occurred at 50–70 m. Some individuals migrated through the area quickly, whereas others used the area for extended periods of time (e.g., months). Although there was some migration of green sturgeon between receivers anchored in the Umqpua River estuary and the ocean receivers, most of the individuals detected on the ocean array were not detected inside of the estuary. These results suggest that the ocean immediately offshore and upcoast/downcoast of estuaries that support green sturgeon may be important green sturgeon habitats, and significant numbers of green sturgeon may interact with wave energy project projects in such areas.