Wireworm with a single wriggling maggot is dynamite in all the prairie reservoirs, i'd imagine same thing up there. I've caught lots on pickeral rigs as well (with smaller hooks of course). They do often cruise a little higher in the water column but use the botton as well. I'm surprised you never see them. I find the biggest trick to catching lots is using a "tippet" of 4-6 lb line, catches the weary ones.