Text and photography copyright 2011 by David W. Lockeretz, all rights reserved. Information and opinions provided are kept current to the best of the author’s ability. All readers hike at their own risk, and should be aware of the possible dangers of hiking, walking and other outdoor activities. The author does not take any responsibility for injuries sustained during hikes or walks on the routes described here. Check the informational links provided for up to date trail condition information.

Diemer Loop in Chino Hills State Park

• Location: Yorba Linda.  From the 57 freeway, take Orangethorpe exit and head east for 4.2 miles.  Turn left on Kellogg, go 1.8 miles and turn right on Yorba Linda Blvd.  Go 0.3 miles and turn left on Fairmont.  Go 1.6 miles and turn left on Rim Crest.  Follow Rim Crest to its end and park on the corner of Blue Gum and Rim Crest.  From the Riverside area, take the 91 freeway to Yorba Linda Blvd.  Go northwest on Yorba Linda Blvd. for 2.4 miles, and turn right on Village Center.  Go a mile and turn left on Fairmont.  Go 0.3 miles and turn right on Rim Crest.
• Agency:  Chino Hills State Park (home page here)
• Distance: 4.2 miles
• Elevation gain: 525 feet
• Difficulty Rating: PG
• Suggested time: 2 hours
• Best season: December – May
• USGS topo map:  Yorba Linda
• Recommended gear: sun hat
• More information: here
• Rating: 5

This is an enjoyable, moderately challenging loop from the Rim Crest entrance of Chino Hills State Park.  The first leg of the trail offers nice views of northern Orange County, and the second half visits secluded Telegraph Canyon.  The wildflowers are particularly brilliant during the spring, but make sure you check the park’s web site to make sure they are open if it has rained recently.

From the Rim Crest entrance, take a left and head west on the South Ridge Trail.  It climbs steeply to a place known as “Glider Point”, supposedly named for the model airplane enthusiasts who like to do their thing here.  The trail continues along the ridge for 1.3 miles, where the somewhat obscure Diemer Trail branches off to the left.  This trail switchbacks down the hill into Telegraph Canyon.

Head right (east) along Telegraph Canyon, Chino Hills State Park’s main trail.  It heads through the woods, crossing a couple of creeks, before arriving at the Easy Street trail.  Take a right, make a somewhat tricky stream crossing, and head back 0.3 miles to complete the loop at the South Ridge Trail.  This last stretch, short as it is, is somewhat steep and runs through a narrow canyon, so be careful.