Trail Stats
Mileage	5.4
Trailhead	1310'
Bridge	1250'
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, is one of the most popular destinations in the San Gabriels. Since the trailhead sits in a residential neighborhood on the edge of a large population, this route is a favorite for walkers, joggers, dog lovers, cyclists, and hikers. The route follows the famed old Mt. Wilson Toll Road all the way to Mt. Wilson, 9 miles. But for the hike to Henninger, you'll be walking 2.7 miles one way.

If you are a hiking purest who prefers trekking on single track hiking trails, I'd recommend making an exception here. The dirt road is wide, well graded, and hosts daily traffic of official vehicles servicing the facility at Henninger Flats. 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 the destination, Henninger Flats, is a real treat, complete with water, picnic tables, a visitor center, campground, and lots of pleasant shade. And it's 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. And summer night hikes to Henninger Flats are popular (see below ).

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 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. Parking on the weekends is restricted, so mind the signs. You may need to park a few blocks away. There is a large fence and gate through which you will walk. (The gate used to have many signs on it—I noticed the new gate on October 30, 2004.) Note that the gate is locked at 8:30 p.m.

Trail Description:

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:

• 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). If you don't want to climb the horse trial, you can continue along the creek until you reach the bridge (1.1 miles from the Nature Center). Turn right and climb the road to Henninger Flats. See Tom Chester's hike report for a more detailed description of this alternate route. 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). From here you have two options. If you turn left you can hike 0.4 mile to the bridge, then turn right to follow the toll road. If you turn right, you can walk two or three minutes to the Walnut Canyon horse trail, turn left and climb steeply to meet the toll road (at the one-mile marker).

• Night Hikes with OCD: Twice a month, Richard Nyerges leads a night hike with the OutdoorsClub.org. On the evening I tagged along (see Hike Log below), there were nine of us. Several took a fairly quick pace while others strolled slower. One lady started a half hour earlier and arrived minutes before the lead group. We enjoyed about 25 minutes at Henninger Flats—snacking, visiting, and viewing the twinkling lights of the cities below. Your first three hikes with ODC are free; after that it's $25 a year.

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:

• 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.

• 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.

• Wild L.A.: A Hiker's Guide - by John McKinney (Olympus Press: Santa Barbara, 2003). "Henninger Flats" Good trail description and historical highlights.This hike is also included in his Day Hiker's Guide to Sourthern California (Olympic Press, 20th Anniversary Edition, 2001) - "Hike 41: Henninger Flats."

Last Hiked: July 28, 2004