Black Diamond Mines Planning

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View from the Clayton Ranch (southern planning area)

Site Description

Black Diamond Mines Regional Preserve (Preserve) is located in east Contra Costa County just north of Mount Diablo. The Preserve comprises a dramatic landscape of high ridgelines and canyons rich in natural, cultural and geologic resources recognized statewide. The Preserve is covered with grasses, shrubs, chaparral, oak woodlands, and the area contains more than 150 rare plant and animal species. The Preserve is located within an area that has been designated a high priority preservation area by the East Contra Costa County Habitat Conservancy (Conservancy), which is a partner with the District in this project.

The purpose of the Land Use Plan Amendment (LUPA) is to set forth a framework for land use and management that maintains a balance between conserving the planning area’s significant resources and providing the public and staff with improved access and facilities and increased opportunities for low-intensity recreational use and interpretation.

The plan proposes public access to over 5,000 acres, bringing the total open preserve land to just under 10,000 acres. The LUP also proposes opening two staging areas, one in the Northern Planning Area and one in the Southern Planning Area; opening two access area with off-street parking; opening five trail heads with multi-use entry points; and opening approximately 25 miles of trails.


The planning area is noted for its geological, botanical and wildlife resources, in addition to its long history of human activity. Existing conditions on the ground reflect millennia of human occupancy, and the land contains a rich variety of cultural resources. The planning area would have likely included the ancestral homelands of two tribes that spoke a language known today as Bay Miwok: the Ompin and Volvon. The Ompin homeland, which centered on both sides of the region where the Sacramento and San Joaquin rivers meet, appears to have extended as far south as the southerly valleys and hill lands of the planning area. The Volvon homeland included the summit of the place now known as Mount Diablo, whose earliest recorded non-Indian name was “Cerro Alto de los Bolbones,” or High Point of the Volvon. The Volvon also held the hill and valley lands east of the summit of Mount Diablo, including most of the planning area lands, with villages located along the easterly drainage of present-day Marsh Creek (Milliken 1995).

The historic period of the planning area can be broken into three periods: the Spanish Period (1770-1821), the Mexican Period (1821-1846), and the American Period (1846 to present). The planning area includes one of the few locations in the San Francisco Bay Area where coal was mined. The discovery of coal in the 1850s led to construction of the Black Diamond Mines, the first source of fossil fuel in California (Sullivan and Waters 1980). By the mid-1870s, mining activity at Black Diamond peaked and five nearby towns were bustling, inhabited with residents primarily emigrating from Wales and Ireland, driven to California by economic depression in their homelands. After the mines closed, some miners found a new career in ranching, and abandoned mining town buildings were repurposed. Nearby towns also shifted to a more diversified agricultural base that included cattle ranching, orchard farming and viticulture.

In 1964, the Park District expanded its boundaries to include a large portion of Contra Costa County; at that time the Preserve was identified as the site for a future park. The Preserve was established in 1973 with the purchase of 2,443 acres of land. When it opened to the public in May 1976, it became the Park District’s first historic preserve. The Preserve has grown since then and today 4,641 acres of moderately to extremely steep peaks and valleys are open to the public. Since 1999, the Park District has added about 5,000 acres of parkland contiguous to the Preserve that is currently closed to the public. This Land Use Plan Amendment will allow for public access on the nearly 5,000 acres that has been closed to the public.

Community Events and Public Hearings

Public Meeting #3 Summary - Jun 2017 (3 pp.)
Public Meeting #2 Summary - Sep 2015 (6 pp.) 
Public Meeting #1 Summary - Nov 2013 (5 pp.)

Project Materials

Notice of Preparation - 2017 (6 pp.)
Project Area Map (1 pg.)
As more information becomes publicly available, it will be posted to this section of the web page.

For More Information

Please contact Chantal Alatorre, Senior Planner at, or at (510) 544-2333 to be added to the project mailing list.


View from Kreiger Peak to Delta, EBRPD

View from Clayton Ranch, S. Joseph

View from Clayton Ranch, EBRPD