Maurice Thorner Memorial Preserve

All visitors must respect rules to keep the preserves safe and sustainable.


  • Hikers only. No bikes or horses
  • No smoking or fires.
  • Weapons and hunting prohibited.
  • Motorized vehicles prohibited. (Individuals with qualified disabilities may operate certain kinds of zero-emission mobility devices on some roads, multiuse trails, and certain other facilities.)
  • No model airplanes, drones, or other self-propelled crafts.
  • Dispose of waste property. Pack it out.
  • Permit required for commercial use and groups of more than 15 people.
  • All resources are protected.


  • Must be leashed at all times.
  • Leash must not exceed 6-feet in length.
  • Allowed on signed trails only. Off-trail use prohibited.
  • Individuals accompanying dogs are required to clean up and remove pet waste.
  • A maximum of 3 dogs per person allowed. No commercial dog walking permitted in this preserve.

In an emergency, call 911. To report an incident or suspicious activity, call the Ranger Field Office at (415) 473-2816 or submit an Incident Report via online form.

Visitors are responsible for knowing and obeying all Marin County Open Space District (MCOSD) regulations. Citations will be issued for violations. Read the official regulations: Marin County Municipal Code Appendix A.

Call (415) 473-6387 for more information regarding allowable types and use of mobility devices for people with qualified disabilities.

The MCOSD is a special district pursuant to the California Public Resources Code. Marin County Parks oversees the management of the county parks system and provides public information on behalf of the MCOSD.