Current Progress | Goals/Objectives | Area Closures | Radar Tower | Project Timeline | Video

The Mount Umunhum Summit project is an excellent reflection of Midpen's three-part mission statement: to preserve open space, to protect and restore the natural environment, and to provide opportunities for ecologically sensitive public enjoyment and education.

Location and Background

The former Almaden Air Force Station at Mount Umunhum, located near Los Gatos, was acquired by the District and added to the Sierra Azul Open Space Preserve in 1986. This high peak, with views as far as Monterey, is special to the military personnel and their families who were stationed there. Mount Umunhum is also important to the Ohlone people as part of their creation belief. Current Santa Clara Valley residents know Mount Umunhum as the intriguing location of the 80-foot-tall,cement radar tower visible for miles. Federal funding allowed the District to clean up the site to allow restoration and public access to this spectacular peak.

Current Progress

  • The Bald Mountain Parking Area is open to the public.
  • Planning for ecological restoration and visitor amenities at the summit is underway. Restoration will focus on naturalizing the topography and restoring native habitat. The summit will be fully accessible to visitors of all abilities and will feature a ceremonial circle, view points, shaded picnic areas, and interpretive features and programs.
  • The Mount Umunhum Trail is currently under construction.  The trail will connect the Bald Mountain Parking Area to the summit of Mount Umunhum, and is expected to open for public use no later than spring 2017 , or as soon as possible following construction and once facilities at the summit have been completed.

Goals and Objectives

The primary goal of the Mount Umunhum Summit Project is to establish a visitor destination that balances public access, enjoyment, and education with environmental restoration. This aligns with two directives of the District's Mission: to protect and restore the natural environment, and to provide opportunities for ecologically sensitive public enjoyment and education. This goal will be achieved through the following:

  • Create a destination that is accessible to and accommodates a broad range of user groups and introduces new visitors to open space.
  • Remove or permanently cap physical hazards and restore the native landscape and habitat for wildlife as much as possible.
  • Provide minimal visitor amenities that complement and highlight the world-class views and open space experience.
  • Provide ample, rich, and diverse trail experiences for hikers, bicyclists, and equestrians.
  • Highlight the rich natural and cultural history of the site through self-discovery and focused interpretive and educational opportunities.

In the near term, providing public access to the summit of Mount Umunhum as soon as possible is a primary goal of this project. Once completed, visitors to the summit will find an ADA interpretive trail, information about the area’s rich natural and cultural history, and expansive views of the entire Bay Area, Monterey Bay, Santa Cruz, and the Sierra Nevada

Closures in Sierra Azul Open Space Preserve

In order to protect public safety and guarantee security, some portions of Sierra Azul's Mount Umunhum area are closed until the site is fully remediated and secure public access can be established.

Please note that the Mount Umunhum and Mount Thayer areas, where remediation work is ongoing, are designated Hazardous Closed Areas. Anyone who trespasses into the area will be cited for a misdemeanor.

Areas that are adjacent to Mount Umunhum and Mount Thayer are declared Temporary Closed Areas. Trespassers will be cited for an infraction. Please refer to the attached map for details.

Radar Tower

Artist Rendering of Interim Action AThe Board voted unanimously to keep the Mount Umunhum radar tower until October 2017 to allow time for supporters and proponents of retaining the radar tower to develop partnerships needed for long-term preservation; however, if no partnerships or additional funding are secured during this time frame, the Board may reconsider all the options based on future funding and staffing constraints. At the same time, the Board approved spending nearly $415,000 for near-term repairs to allow the public access to the exterior base for a period of five years following construction; these repairs are currently underway.

Project Timeline

October 2017 Deadline for proponents of the tower to establish and develop partnerships, funding, and other resources to allow for implementation of Option 3, Retain and Seal (per Interim Action A).
November 2014 Bald Mountain Parking Area open to the public.
February 2014 Demolition of structures (except the radar tower) complete at the former Almaden Air Force Station, 95% of the building materials were recycled.  As a part of the demolition work, erosion control measures were installed, and slopes were re-contoured as much as possible to match the original ridges and swales that existed prior to construction of the Almaden Air Force Station.
February 2013 $1 million grant received from the California Coastal Conservancy. The grant supported project implementation and fund a majority of the construction costs for the Bald Mountain Parking Area, Mount Umunhum Trail, and visitor amenities at the summit.
October 2012 The Board of Directors selected Interim Action A: Near-term repair and securing of structure while considering external partnerships.
July 2011 The Army Corps of Engineers contractor completes hazardous materials remediation work.


On Sunday, May 3rd, Open Road featured a story about the restoration work in progress on Mount Umunhum.  Segment begins at 6:20.

On July 20, 2011, KQED QUEST aired a television piece entitled Mount Umunhum: Return to the Summit, that shows the mountain before project work began.


Contact Information


For questions or comments regarding the Mount Umunhum Summit Project, please contact Meredith Manning, Senior Planner.


  • Bald Mountain Parking
    The new Bald Mountain Parking area is now open to the public
  • Bald Mountain Groundbreaking
    District Board Members, Staff and Partners gathered together for the Groundbreaking for the Bald Mountain Parking Area on April 23, 2014. © Jack Gescheidt
  • nest box
    Nesting boxes for rare Purple Martins installed on the summit
  • Mount Umunhum Summit
    Sunrise at the summit
  • Mount Umunhum vista
    A brand new vista has been opened up where buildings once stood. Looking west towards Ben Lomond Mountain in the distance.
  • Mount Umunhum demolition
    Clean wood from demolished buildings was ground into mulch and used onsite for erosion control.