We found this cool little anchorage called Martin Slough, on the north side of the Columbia. The approach is a little shallow, but no problem at this time of the year, with the river near flood stage. There were a few boats in the anchorage already, so we picked a spot we thought was far away from the other boats, but once we had let out our anchor chain, we thought our swing radius was too close to a trawler. We didn't want to worry about it, so we raised the anchor and dropped it again about 100 ft back. This time, we landed pretty close to shore, but after monitoring our swing, decided it would be ok. Our Furuno chart plotter has an anchor watch feature that you can set in the cockpit and at the nav station independently of each other. During the evening, we set both so we could hear the alarm in either the cockpit or in the cabin. At night, we set the anchor watch at the nav station only, to conserve amps. We also have a handheld Garmin GPS that has an anchor watch, so if we are worried about dragging anchor, we can set the handheld anchor alarm in the forward berth as well. Depth was 30ft, so we let out 200ft of scope (almost 7:1).