Access Note: The torrential rains of January 2005 caused a massive landslide near the beginning of the road and several smaller slide higher up on the road, prompting authorities to close the road and Henninger Flats. See photo. Even though the road is still officially closed, over the last several years trail users have worn use paths through the slides and the closure does not seem to be enforced. See Access Note below. To hike to Henninger Flats currently, you can use one of the two alternate routes described below. Read news article: Mountain fire road to be cleared (7-18-08, San Gabrial Valley Tribune) On August 12, 2008, the Board of Supervisors approved the repairs and restoration of the Mt. Wilson Toll Road. Work is scheduled to begin in October 2008 and be completed by April 2009. We'll see.

Trail Stats These are for the Toll Road trailhead, which is still closed, but they are still pretty close to the stats for the alternate routes below.
Mileage	5.4
Trailhead	1310'
Henninger Flats	2550'
Total loss/gain	1360'
Gain/loss per mi.	504'

Henninger Flats, a forested notch sitting conspicuously on the mountain slopes above Altadena, was one of the most popular destinations in the San Gabriels until the landslides. Since the trailhead sits in a residential neighborhood on the edge of a large population, this route was, a favorite for walkers, joggers, dog lovers, cyclists, and hikers. The traditional route follows the famed old Mt. Wilson Toll Road. But with the main gate now closed, you can use the Midway trailhead or Visitor Center to access the road via the Walnut Canyon horse path. From the Midway trail head it's about 2.5 one way to the flats (from the Visitors Center is a little longer). If you're going all the way to Mt. Wilson, it's about 9 miles one way.

If you are a hiking purest who prefers trekking on single track hiking trails, I'd recommend making an exception here. So why hike a dirt road? One good reason is for the outstanding city views all the way up, especially in the non-summer months when the air is fresh and the visibility clear. And since the road is closed now to vehicular traffic, the route feels a little more like a traditional hiking trail, particularly in those spots that traverse the lands slides. And the destination, Henninger Flats, is a real treat, complete with water, picnic tables, and lots of pleasant shade. Even though the visitor center and campground are official closed right now, Henninger Flats still makes a nice destination.

Henninger Flats is home to the Los Angels County Experimental Forestry Nursery.

Season: November - June

Generally speaking, the front range of the San Gabriels is best hiked in the cooler months, and the back range is best in the warmer months. Henninger Flats sits in the front range. Walking there on a hot summer day, with the full wrath of the sun beating down on you the whole way, can be miserably punishing. But the route still gets a lot of use in the summer, primarily early morning, late afternoon, or early evening. Early in the summer the "June Gloom" (marine layer, coastal fog) can make nice walking conditions but also can greatly obscure your views.

Getting to the Trailhead:

On the I-210 Foothill Freeway driving through Pasadena, eastbound, exit at Sierra Madre Boulevard/Altadena Drive. Turn left (north) at the first light (Altadena Drive). From the I-210 westbound, exit at San Gabriel Boulevard/San Marino. Turn right (north) at the second light (Altadena Drive). Follow Altadena Drive about 1.5 miles to New York Drive. Continue up Altadena Drive about one block and look for the Eaton Canyon Nature Center entrance on the right. Turn in here for the route from the Nature Center.
       If you are taking the Midway trail, continue up Altadena Drive and drive about 0.5 mile to where Roosevelt Avenue and Midwick Drive intersect on the left. The trail begins at the pedestrian gate on the right.
       If you want to see the closed gate for the Mt. Wilson Toll Road, continue on Altadena Drive for about another mile and turn right unto Crescent. Go about 200 yards to Pinecrest, turn right and go about 200 yards to the Mt. Wilson Toll Road, on your right. You have a good view of the large landslide from here, but the locked gate prevents you from taking this route until the toll road is open again.

Trail Description:

[Note: the following description will be doable once the toll road is open again. See Alternate Routes below for current hikes.] Walk through the gate and down the road into Eaton Canyon. You'll descend about 60 vertical feet before crossing bridge and heading up the road. The route climbs steadily. If you need a rest, take advantage of the well-placed park benches perched along the way. At the one-mile maker you pass the junction for the trail coming up from Eaton Canyon (see Alternate Routes below). Continue climbing as the views of the San Gabriel Valley below open up. In a few tenths of a mile past the two-mile marker, you will cut back to the left on the last of five major switchbacks. You're now on the final pitch and in a few minutes you'll be passing the Henninger Flats sign and descending gently to your destination.

You can easily spend a couple hours at the visitor's center and exploring grounds. If you would like to extend your hike, you can follow the road through Henninger Flats up to the ridge overlooking the flats to the south and Eaton Canyon to the North. Once at the ridge, turn left and follow the fireroad road that loops around the ridge to a heliport. Enjoy a great 180-degree view of the city below.

Return the way you came.

Trail Notes:

• Access Note: The torrential rains of January 2005 caused landslides that blocked the road to Henninger Flats. See photo Even though the road is officially closed, over the last several years trail users have worn use paths through the slides and the closure does not seem to be enforced. I hiked to Henninger Flats on June 29, 2008, and this is what I found:
  

  VISITOR INFORMATION Henninger Flats continues to remain closed due to the storm damage of 2005. As a result the campgrounds, visitor center and restrooms remain closed. There is NO CAMPING at Henninger Flats. Nature trails are also closed for safety due to erosion damage. If you would like further information, please ask the on duty forester or call (626) 794-0675. Idlehour trail head is approximately 1.5 miles up the Mt. Wilson Toll Road, with a 1.5 mile hike into the campground. The road continues to Mount Wilson for approximately 6.5 miles. Watch out for vehicles.

  Signs: There are still "Road Closed" signs on the locked gate at the beginning of the road at Pinecrest. However there are no signs at the Roosevelt/Midwick trailhead and no signs at the trail junction for the horse trail starting up Walnut Canyon. In other words, even though those answering the phone at the Eaton Canyon Nature Center say the road is closed, there is no effort in restricting foot traffic at the point of entry. On the "Lower Camp Grounds" sign, there was a small paper-in-plastic sign saying, "Henninger Flats is Closed Until Further Notice." There's also a Visitor Informationsign posted on a bulletin board near the visitor center at Henninger (see side bar on right). The contents of that sign imply to me that we are welcome to pass through Henninger Flats en route to other places, we just aren't allowed to use the facilities. It also implies that hikers will be hiking up the "closed" road, and gives no prohibition against it. A couple years ago when I spoke with one of the foresters, he said they were strictly enforcing the closure of the road and issuing citations for trespassers. That does not seem to be the case now.
  Landslides: There are 5 slides between where the horse trail reaches the toll road and Henninger Flats. They all appear to be stabilized and users have carved well-worn use paths through them. They will need some heavy earthmoving and engineering to get the road back in service for vehicles, but for pedestrians, the route seems perfectly fine. I think the reason for the closure now is simply "cover your a_ _ " government bureaucracy. You can check with the officials, but they'll just tell you not to hike there: Forest Service; Henninger Flats Nature Center: 626-794-0675.
  My advice: Go hike to Henninger Flats! See alternate routes below.

• Alternate Routes:
  From Eaton Canyon Nature Center - Park at the far north end of the parking lot. Follow the path north and across the creek. Veer left and follow the trial along the north bank of the creek. At about a half mile from the creek crossing, you can turn right into Walnut Canyon and take the horse trail which climbs steeply up 12 switchbacks to meet the old Mt. Wilson Toll Road (at the one-mile marker). Turn right (east) and climb the road to Henninger Flats. See the Eaton Canyon links below for more details.
  Midway trail - From Eaton Canyon Park, turn right unto Altadena Drive and drive about 0.5 mile to where Roosevelt Avenue and Midwick Drive intersect on the left. The trail begins at the pedestrian gate on the right. Walk through the gate and follow the trail as it drops to the canyon bottom. Cross the creek bed to intersect the main trail on the east bank (0.2 mile). Turn right walk a minute to the Walnut Canyon horse trail, turn left and climb steeply to meet the toll road (at the one-mile marker). Turn right (east) and climb the road to Henninger Flats.

Hike Log Henninger Flats - Night Hike 7-28-04 7:38 PM A: Trailhead (1310') 7:51 B: Mile 1 / Trail Junction 8:14 C: Mile 2 8:27/8:54 D: Henniger Flats sign (2550') 9:06 C: Mile 2 9:25 B: Mile 1 / Trail Junction 9:42 PM A: Trailhead (1310') Summary: 49 Minutes up 48 minutes down 26 minutes on top

View Full Topo Map (216 K)

Related link on Dan's Hiking Pages:

• Eaton Canyon Falls - via Eaton Canyon Nature Area

Links:

• Mountain fire road to be cleared - Read news San Gabriel Valley Tribune article (7-18-08).

• LocalHikes.com - "Henninger Flats" - by Sandy Westphal. Brief summery, directions to trailhead (somewhat confusing), and photos. Note, her topo map traces the wrong trail!

• Altadena to Henninger Flats - by Tom Chester. Detailed detailed trip log, links, and report for the hike starting at Eaton Canyon Nature Center.

• L.A. County Forestry Division - Henninger Flats - Visit the official website of the LACoFD -- Provides informaiton about Henniger Flats history, visitor center/museum, trails and campgrounds, and service opportunities. Phone: 626-794-0675.

• Eaton Canyon Nature Area - Provides a brief description and aeral photograph of trails in Eaton Canyon, including variations for the hike to Henniger Flats. The center is also a great place to learn about nature (1750 North Altadena Drive, Pasadena, CA 91107 / 626-398-5420 - Open 9:00 - 5:00 daily). Excellent online catalog of native plants of the San Gabriels. Driving directions and map to Eaton Canyon Nature Center.

Books:

• Trails of the Angeles: 100 Hikes in the San Gabriels - by John Robinson (Wilderness Press). See hikes 26 through 28. Good trail descriptions with historical background. Describes the route from the gate on Pinecrest Drive. Puts the round trip at 5 miles with 1,400 feet gain.

• Afoot and Afield in Los Angeles County - by Jerry Schad (Wilderness Press, Second Edition, Sept. 2000) - Area A-6, Trip 10: "Henninger Flats." Good trail description and historical tidbits. Describes the route from the gate on Pinecrest Drive. Puts the round trip at 5.4 miles with 1,400 feet gain.

• Los Angeles County: A Day Hiker's Guide - by John McKinney (The Trailmaster, 2006). "Henninger Flats." Good trail description and historical background. Describes the route from Nature Center using the horse trail. Puts the round trip at 6 miles with 1,400 feet gain. Previously published in Wild L.A.: A Day Hiker's Guide (2003), now out of print.