Be careful with the type of anchor system you use. Way back when we used to set a course in the river, the anchors would often take a hard set after a full day of the current pulling all the bouys, pvc, & rope (plus never know what's down there in a river bottom).

Make sure you've got a good retrieval method. Nastiest scuba trip I ever took was to retrieve a course anchor in the river when we couldn't pull it up. Zero visibility and no real bottom - the muck just got thicker the deeper you went. I smelled so bad they wouldn't let me back in the boat...