SDC Coalition


At almost 1,000 acres, the Sonoma Developmental Center (SDC) property is the largest and most significant unprotected land in the Sonoma Valley. In addition to providing services for developmentally disabled individuals, this property is situated at the heart of the Sonoma Valley wildlife corridor, a crucial passage for wildlife that extends over 5 miles from Sonoma Mountain to the Mayacamas Mountains and is at risk of being developed.

The SDC Coalition is working to:
Sonoma developmental center sonoma mountain

  • Advocate for the permanent protection of the open land on the SDC property and the essential services it provides, such as habitat and movement corridors for wildlife, clean and ample drinking water, a place of beauty for us to enjoy, and carbon sequestration.
  • Expand public access and recreation opportunities compatible with the protection of the property’s conservation values, including the development of new trails and connections to existing trails on Sonoma Mountain, and potentially across Sonoma Valley to the complex of protected lands within the Mayacamas Mountains.
  • Explore new uses for the campus that remain within the developed footprint and are complementary to both the property’s natural values and the surrounding community.

Coalition members include: Audubon Canyon Ranch, Parent Hospital Association, Sonoma County Agricultural Preservation and Open Space District, Sonoma County Regional Parks Department, Sonoma County Water District, Sonoma Ecology Center, Sonoma Land Trust, Glen Ellen Forum, Sonoma Mountain Preservation, Valley of the Moon Natural History Association, Supervisor Susan Gorin, Congressman Mike Thompson, Assemblymembers Cecilia Aguiar-Curry and Marc Levine, and State Senators Mike McGuire and Bill Dodd.

What Is at Risk

Incompatible redevelopment of the SDC campus and adjacent open space would have far-reaching consequences for residents of Glen Ellen and the greater Sonoma Valley in terms of traffic, wildfire risk, and impacts to quality of life. Bad development would also negatively impact the regionally important wildlife corridor, adjacent critical habitat for fish and wildlife, and the potential for recreation and public access. 

SDC is at the heart of Sonoma Valley's wildlife corridor. Map courtesy of Sonoma Land Trust.

SDC is at the heart of Sonoma Valley’s wildlife corridor. Map courtesy of Sonoma Land Trust.

Diverse Habitat and Connected Corridors for Wildlife

Sonoma developmental center coalition sonoma mountainThe SDC property contains oak woodlands, Douglas fir forests, redwoods, grasslands, lakes, wetlands, and streams. Deer, mountain lion, coyote, bobcat, and rare species such as steelhead trout, northern spotted owl, and California red-legged frog live here. Sonoma Creek, which runs through SDC for about three-quarters of a mile, is one of the county’s most significant streams for steelhead. In addition, the property provides significant water resources for the surrounding community.

Permanent protection of the undeveloped portions of the SDC will link over 9,000 acres of protected land home to many rare native plants and animals. The property is recognized as a regionally significant linkage connecting the Marin coast to the interior Coast Ranges of California. SDC is the last large undeveloped property in Sonoma Valley, and the loss of its exceptional habit to incompatible development will likely have devastating effects on wildlife movement across the Valley.


Sonoma Developmental Center mountain preservation SDC is the single large property in Sonoma Valley poised to recreationally connect Sonoma Mountain and Jack London State Park to Sonoma Valley Regional Park, with its network of publicly accessible lands, bikeways, and transit operations that link to Sonoma and Santa Rosa.

There is substantial existing public investment in the land, featuring more than 12 miles of trails and two scenic lakes enjoyed every day by the public. The general topography supports accessible trails that appeal to all segments of the population. This property can provide access to nature and healthy lifestyles in a way that no other Sonoma Valley facility can.

Thanks to First District Supervisor Susan Gorin’s office for this information.