As of early 2020, erosion has cut off the trail that connects the Bull Creek Flats Trail South to the Rockefeller Loop at about the midway point of the recommended hike. The connector trail now ends at a 20 foot dropoff, making it very difficult to cross over to Rockefeller Grove. It also seems unlikely that the seasonal bridge will be installed. The trail has been this way for at least a year.
Instead of using the route shown on the map below, continue east on the Bull Creek Flats Trail South for an additional 0.3 miles to the River Trail, then turn left to reach a second crossing. This crossing has also been eroded, but an alternate trail (marked with ribbons) has been constructed that makes it much easier to climb down to the creek and cross over to the Rockefeller Loop. It’s not clear if this trail is official and it still requires a bit of a scramble down to the creek, but it’s currently the best option.
The crown jewels of California’s redwood forests are the alluvial flats, the fertile floodplains that line year-round creeks, where the most spectacular stands of redwood grow. Bull Creek Flats is the biggest old-growth alluvial flat of all; it’s home to what has been called the world’s tallest forest.
This day-long loop takes in almost all of the magnificent Upper and Lower Bull Creek Flats. The pleasant, easy meander includes several of the most impressive redwood groves anywhere.
The loop isn’t perfect; a lot of the trail goes around the best groves instead of going through them, so the hike actually feels like a series of 6 or 8 small alluvial-flat groves separated by long stretches of more mundane forest. On the north side of the creek the stillness of the redwoods is interrupted by an occasional passing car, and parts of the trail run right next to the road.
The full loop can only be hiked in the summer and fall because it includes a seasonal footbridge that’s normally installed between mid-May (but sometimes not until the end of July) and late September. At other times the creek may still be only a few inches deep and easily forded. When the footbridge is out and the creek becomes a raging torrent, the best alternative to the full loop hike is an out-and-back on the Bull Creek Flats Trail South.
The loop can be started from either end or in the middle at the Big Trees Area. In the summer, the loop can be shortened by crossing Bull Creek on a seasonal footbridge at the Big Trees Area.
The south side of Bull Creek is fairly popular and in summer it’s normal to see someone every 5 or 10 minutes. On the north side, the it’s rare to see people outside of Rockefeller Forest and the Big Trees parking lot.
Here’s the trailhead location in Google Maps.
Bull Creek Flats Trail South starts at Grasshopper Road, where there’s enough parking for several cars. The trail begins in a scenic alluvial-flat redwood grove, but soon climbs onto a hillside with few redwoods. From here until the Big Trees area the trail is pleasant if not spectacular. In the winter, it’s also slow going because it gets very muddy; fortunately it’s the only part of the loop that gets muddy.
The scenery improves dramatically as the trail descends to the Big Trees Area, which is one of the best parts of the hike. The trail winds through the impressive cathedral-like forest, passing two side trails that lead across the creek to the Big Trees Area parking lot. After passing the second of these trails, the trees get a little smaller and the forest less open, but it’s a subtle difference and the forest continues to be quite impressive for another mile.
The trail emerges from the redwoods for about a quarter-mile. After re-entering the forest, the trail climbs perhaps 20 or 30 feet up the hillside at the edge of the flat. It remains at that slight elevation, contouring along the hillside for another mile or so. Although the trees on the flat below are quite spectacular, the big old growth stops abruptly at the edge of the flat. As a result this part of the trail is less engaging because you’re no longer walking among the big trees, but looking at them from a distance. Sadly, the trail actually used to go through the flat but was re-routed onto the hillside.
The trail briefly descends to the flat again but then, in one big switchback, climbs even further up the hillside into redwood uplands. As is typical of upland forests, the redwoods are much smaller here and there’s a dense understory of huckleberry bushes. This is the transition between Upper Bull Creek Flat and Lower Bull Creek Flat.
Take the first trail to your left, which makes a scenic descent to a small flat with a very open and somewhat dark old-growth grove. The trail cuts across the flat and crosses Bull Creek on a seasonal bridge.
The north side of Bull Creek feels less remote and less pristine than the south, but it has more big-tree alluvial flat groves.
The Bull Creek Flats Trail North begins to your left just as you enter Rockefeller Grove. Although it’s not included in the milage for this hike, I highly recommend taking a 0.6 mile detour and walking around the Rockefeller Loop Trail, which circles around Bull Creek Flat; huge redwoods are especially dense here and the trail is definitely a highlight of Humboldt Redwoods. Traffic noise from Highway 101 is sometimes audible but is not overwhelming.
As it leaves the Rockefeller Loop behind, the Bull Creek Flats Trail North continues through exceptional old growth. There’s a break in the redwoods and the trail is briefly squeezed up against Mattole Road as it passes from Lower to Upper Bull Creek Flat. The trail loops around a little flat with some nice redwoods, located between the upper and lower flats. There’s another break in the redwoods as the trail runs just below Mattole Road again for a short stretch.
The trail then enters Upper Bull Creek Flat. Plunging into the redwoods, the trail passes through a series of what look like three small but very attractive redwood stands. In fact, these stands are actually a single large grove that the trail mostly skirts around and only occasionally dives into. The first stand is a spectacular cathedral-like grove as fine as any in Humboldt Redwoods. The next two follow over the next mile or so and aren’t quite as open, their understory dense with small tanoak trees, but they’re still pretty scenic. Despite the great scenery, this part of the trail is little-known and few people make it out here.
A few stretches of the trail are very close to Mattole Road and the traffic noise can be annoying on a summer weekend. In contrast, on a winter weekday there might only be a car every 10 or 20 minutes (although in the early morning there seem to be a lot of trucks headed for the Lost Coast) so the road isn’t as noticable.
Near Look Prairie, the flat ends and the trail runs right next to the road for a while; it’s advisable to just walk on the road here since the trail is somewhat rough and infested with poison oak. The trail then disappears completely, joining the road as it curves along Bull Creek past a clearing that offers a little sunlight and some very nice views of tall redwoods growing along the creek. There’s a dirt parking lot, the Blue Slide Day Use Area, to your left. The trail begins again, skirting around the lot and diving into the forest. The trees get noticably bigger as you approach the Big Trees Area parking lot.
Past the parking lot, the trail enters an especially scenic grove. This is the longest and one of the most impressive stretches of big-tree alluvial flat scenery on the hike. There are glimpses of tapering sunlit treetops and impossibly tall and thin light beige trunks shooting high into the sky. This grove exemplifies the "cathedral-like" redwood forest, with the fluted columnar trunks illuminated by flecks of sunlight filtered through the stained-glass canopy. In winter, the pleasant sound of rushing water permeates the area.
The best scenery continues for about a third of a mile, after which the trail moves closer to the river and skirts the edge of the forest, where the redwoods are much smaller. The Big Trees Trail ends at Mattole Road; turn left onto the road to cross Bull Creek and reach the end of the hike.
© 2007, 2010, 2016, 2018 David Baselt