I've always used long leaders while trolling plug-cut herring for springers, 9 to even 12 feet, for all lower Columbia fisheries, from Drano, Wind and on down to Cathlamet. Usually use it with just a drop sinker, 2-4 ounces, but this year at Cathlamet tied on a green 6-inch Fish Flash and/or Kone Zone about 18 inches behind the sinker to good success. Fished there Wednesday and Thursday with that rig and limited both days. Used 12 pound test main line and leader.