The Sonoma Developmental Center's next chapter runs through environmental review

GLEN ELLEN: The future of the Sonoma Developmental Center, the 945-acre former state facility at 15000 Arnold Drive in Eldridge, is being written through one of California's most watched planning processes: a specific plan backed by a program-level environmental impact report.

The campus closed as a developmental center years ago, and the state has been working through what comes next ever since. The specific plan would set land uses for the developed core, while the program EIR analyzes the environmental consequences at a planning level, with project-level review to follow for individual developments.

Courtesy of Sonoma Land Trust

One large piece is already settled. In early 2024, 650 acres of the property's open space were transferred into the state park system, securing the ridgelands and wildlands around the campus core for conservation and public access. That transfer took the most ecologically sensitive land off the development table before the planning debate began in earnest.

What remains contested is the developed core: the historic buildings, the infrastructure and the question of how much housing, and what kind, belongs on a campus the state is effectively redeveloping from scratch. Glen Ellen residents have followed every iteration closely, and the EIR process is where their concerns about traffic, water, fire safety and historic preservation get formal answers.

Sonoma Land Trust, which has run a dedicated program around the property's transformation, describes the site as one of the most consequential land-use decisions in the valley's recent history. The trust's interest is the open space and habitat connectivity; the county's interest is housing and a coherent plan for state-owned land.

Via Wikimedia Commons

The EIR process is slow by design: draft, public comment, responses, revisions, certification. Each round generates thousands of pages and months of debate. The Post will track the milestones as the document moves toward certification and the plan moves toward adoption.