text: If I dissect the island in JOSM, it turns out there are two ways there: a "place=island" with name and access tags as an inner way of the Columbia River multipolygon, and a "landuse=military" polygon traced over it.
  
  As for naming, neither the USGS topo maps nor GNIS has a name for it.  Bing Maps/Here is unaware that the island exists, as is MapQuest/Mapbox Terrain.  Google Maps calls it "Carpet Island".  Benton County knows about it but doesn't give it a name.  The "name_2" of "Carbody Island" gets zero Google hits.