the Rancho San Antonio ridgeline

Ridgeline Easement Protection at Lehigh Quarry

In August 2021, Midpen and the County of Santa Clara both approved a Memorandum of Agreement to share enforcement of the 1972 Ridgeline Protection Easement, which preserves the scenic ridge between Rancho San Antonio County Park and Open Space Preserve and Lehigh Quarry.

An inspection of the Ridgeline Easement will be scheduled at a later date. Any violations of the easement will be discussed as they arise.

aerial view of a ridgeline and the quarry beyone
The Ridgeline Protection Easement highlighted in pink.
Natural Resources Protection and Restoration
Natural Resources

Santa Clara County holds a Ridgeline Easement over portions of Lehigh Quarry, just south of Rancho San Antonio Preserve. This ridgeline protects the viewshed, reduces dust from quarry operations from exiting the quarry, and establishes a buffer between the quarry and adjacent natural preserve to protect local wildlife. The Memorandum of Agreement allows Midpen to support the original intent of the easement to protect the ridgeline and surrounding viewshed.

Read the Santa Clara County Ridgeline Easement Report.


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Ridgeline Protection Easement

Lehigh Hanson is a cement company, owned by Heidelberg Cement, that operates the Permanente Quarry near the city of Cupertino.

In 1972, the Santa Clara County Board of Supervisors and Kaiser Cement & Gypsum Corporation, Lehigh’s predecessor, agreed to protect the ridgeline between the quarry and what is now Rancho San Antonio Preserve by entering into a Ridgeline Protection Easement to permanently prevent mining, quarrying or other activities from lowering the ridgeline.


Regulatory Agencies

The quarry operations are regulated by numerous government agencies including agencies that regulate air quality, water quality and wildlife. Santa Clara County has oversite and approval authorities over Lehigh Quarry in regard to reclamation plans (through state mining reclamation law), permitting and the determination of the extent of vested mining rights. Santa Clara County also owns the Ridgeline Easement. Midpen is not a regulatory agency but is engaged in protecting the Ridgeline Easement and has a number of concerns about the proposed 2019 Reclamation Plan.

Proposed 2019 Reclamation Plan Amendment 

Lehigh Hanson has proposed an amendment to their existing Reclamation Plan that includes an expansion of mining activities, including in the area of the Ridgeline Protection Easement. Midpen is concerned about the potential environmental impacts of the proposal and has formed an Ad Hoc committee of its Board of the Directors to focus on the 2019 Reclamation Plan Amendment. Midpen has identified a number of critical issues and concerns and shared those in writing with Lehigh Hanson: March 23, 2021, Letter to Lehigh re Reclamation Plan

Midpen has no regulatory authority over Lehigh Hanson and has no permitting or regulatory discretion over the quarry operations.


Staff contact: Senior Resource Management Specialist Aaron Hebert,, 650-691-1200.