The Nature Conservancy is working to preserve a vast natural area in central California’s Diablo Range between the rapidly growing Silicon and Central Valleys. The 1,875 square miles—1.2 million acres—of Mount Hamilton and its surrounding foothills are home to some of California’s finest oak woodlands and an amazing diversity of species, including the rare bay checkerspot butterfly and wintering bald eagles. The area’s creeks are a major source of drinking water for nearby residents. The Conservancy’s Mount Hamilton Project seeks to protect the most ecologically critical 500,000 acres of this landscape by working with local cattle ranchers, public agencies, and other partners.

Peregrine falcon © Frank Schleicher

Strategic Importance

• Preservation Impact: Safeguarding these private lands, largely cattle ranches, will create a circle of protection around the core of the wilderness, and connect the extensive public lands in the area, including state, county and regional parks, university lands, and water district holdings.
• Ecological Significance: This pristine landscape of oak woodlands, sycamore valleys, stream-fed canyons and pine-topped ridges is home to several threatened and endangered species. Its creeks are a vital water source to the South Bay, providing 50 percent of the area’s drinking water. But it is facing intense development pressure from two burgeoning population centers: the Silicon Valley to the west and the Central Valley to the east.
• Partners: Santa Clara County Open Space Authority, Land Trust for Santa Clara County, Silicon Valley Conservation Council, Green Foothills, Greenbelt Alliance, Santa Clara Valley Water District, California Department of Parks and Recreation (Henry Coe State Park), California Department of Fish and Game, California Wildlife Conservation Board, East Bay Regional Park District, San Francisco Water Department, University of California, Santa Clara County, City of San Jose, Santa Clara Valley Transportation Authority, Santa Clara County Parks District.
• Plans: The Mount Hamilton Project, launched in July 1998 with the acquisition of the Simon Newman and Romero Ranches, seeks to protect another 50,000 acres of wilderness land through outright acquisitions and conservation easements. Lakeview Meadows Ranch was bought in February 1999. The Conservancy has designed a stream restoration project that will protect the three major streams in the area, improve the water quality and allow for the establishment of seedling trees and natural regeneration of native plants.

Mount Hamilton Project Facts

• Project Area: 1,875 square miles, about 1.2 million acres
• Acquisitions: more than 81,000 acres 
• Location: in the central Diablo Range east of San Jose (Santa Clara, San Benito, Stanislaus and Merced Counties)
• Plant Species: valley oak savanna on the western slopes; blue oak woodlands on the drier eastern slopes
• Animal Species: bobcats, mountain lions, the San Joaquin kit fox, golden eagles, wintering bald eagles, red-tailed hawks, California tiger salamander, red-legged frog, western pond turtle, rainbow trout, foothill yellow-legged frog, bay checkerspot butterfly

Lakeview Meadows Ranch    © Gary N. Crabbe

• The University of California’s James Lick Observatory at the summit of Mount Hamilton provides dramatic views of the entire area. The observatory offers guided tours of its facility and historic telescope. For information, call (408) 274-5061 or visit the observatory’s web site

For information on the parks, visit their web sites:

• Henry Coe State Park
• Pacheco State Park
• San Luis Reservoir State Recreation Area
• Anderson Lake County Park
• Coyote Lake County Park
• Joseph D. Grant County Park

Learn more

• About The Nature Conservancy's success stories worldwide
• About how The Nature Conservancy works to achieve conservation results