Agua Chinon Canyon to the Sinks and Round Canyon Exploration Day: 7:30 AM Entry Only

Special Events

Please print your auto-generated confirmation email from  before you arrive.

Start your weekend off by exploring the Agua Chinon wash and the Sinks through this self-guided opportunity. Designated trails will be open for self-guided trail use in OC Parks’ Irvine Ranch Open Space. Trail routes vary in distance and level of difficulty with choices ranging from easy one-hour walks to a strenuous 9.5 mile trek. Whether traveling by feet or on two wheels, this exploration day is a treasure waiting to be discovered by hikers and mountain bikers alike.

The Round Canyon Exploration opportunity is a quick out and back hike with a 2.5 mile gradual 370′ elevation climb into a small canyon oasis. Tucked into the western cismontane of Loma Ridge, this canyon is part of the Limestone Canyon Preserve and it is rich in biodiversity. After the 2007 Santiago Canyon Fire, this little canyon saw a sudden re-growth of uncommon flowers, specifically the Wild Peony. The high canyon walls create a wonderful slope effect to the local coastal sage scrub community, noting large patches of Prickly Pear Cactus, Laurel Sumac and Lemonadeberry Bush. This canyon is thick with Coast Live Oaks and offers a rich birding experience. To access Round Canyon, visitors will need to hike or bike 0.75 miles along a paved frontage road that includes a steep descent along a flood control basin before reaching the trailhead.

Visitors to the Open Space during this activity are able to hike or bike to both the West and East Sinks Viewing Decks as well as Round Canyon.

Reviewing the 1-through-5 Difficulty Ratings will help you evaluate your readiness to participate in this level-3 to 4 activity on the land.

Please note that you will be asked to adhere to the following protective measures during the activity in order to participate:

All participants are required to have a printed copy of their confirmation form for entry to this event. Be registered in advance, and no walk-up registration is permitted at the Portola Staging area. Please note parking is limited.

The West Sinks route is 6 miles round trip with a challenging up hill climb while a visit to the East Viewing Deck is a strenuous 8 miles round trip and may take the majority of the designated activity time. Please review our Trail Tips page and FAQ page to prepare for this challenging hiking and biking opportunity.

Be sure to cancel your registration if you cannot attend so that other participants can register. No walk-up registrations will be allowed on site.

  • Arrive with all necessary equipment to keep you safe on the trail, including plenty of water, proper attire to protect you from the sun and closed-toe footwear, first aid, medications, hand sanitizer, etc. Please see Trail Tips on the Lets Go Outside website for more tips.
  • Maintain proper physical distancing, a minimum of 6 feet, between yourself and participants who are not in your household.
  • Bring and make use of recommended facial coverings while in the staging area and when on trail if you are unable to maintain 6′ of distance from others.
  •  There will be one-way directional signs on the trail system. Follow these signs to help best minimize for the safety of all trail users at the event.
  • OC Park Rangers require all trails to be cleared for closure by 11AM.
  • Minors, ages 18 and under, should be accompanied by a parent or guardian.
  • Adult mountain bikers are requested to wear helmets. Minors are required to wear helmets per state law.
  • Motorized recreation vehicles of any class or type are not permitted for recreational use.
  • No new trail users will be permitted onto the trails at least one hour prior to closing.

Multi-use trail etiquette: Please remember that bikers yield to hikers when sharing the trails. Click here for more trail tips.

We suggest forwarding the confirmation email to your registered guests.

To learn more about the staging areas and activity locations, please visit our Staging Areas Playlist page.

Activity Details Led by IRC

Saturday, October 17, 2020
7:30 am - 11:00 am
Special Events
OC Parks
Limestone Canyon Nature Preserve
Staging Area:
Portola - Agua Chinon
Elevation Change:
Minimum Age:
All Ages
Family Friendly:
Spaces Left:
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