The northern portion of the trail between Caroline's Loop is prone to flooding during the rainy season and the water will usually pool in the Dinosaur Track area. Although not impassable, the water can be close to a foot deep.
Joe Johnston is the main trail of the GCSNA Backcountry area. It begins at the Backcountry trailhead and connects to all of the other trails except for Far Reaches Trail.
It begins at a rough dirt road and eventually flows into singletrack closer to Caroline's Loop. The trail is littered with loose rocks throughout. You'll cross three different low points that will flood if there has been rain. Also, look out for riders as this is the trail that they will heavily traverse.