Ontario, CA Historic Preservation: Historic-Cultural Monuments (2026)

Ontario's Historic Preservation Article, enacted by Ord. 2707 (effective December 16, 1999) and codified at OMC Sec. 2680, makes it a misdemeanor to violate any requirement of the Article or to disobey an order of the Historic Preservation Commission or a condition attached to a certificate or permit issued under it. Unauthorized alteration or demolition of a Historical Resource is expressly declared a public nuisance: the responsible person or entity must restore or reconstruct the property to its condition before the violation, and is separately liable for a civil penalty.

That penalty is calculated as one-half the resource's assessed value prior to demolition, or one-half the cost of restoring the altered portion for a partial alteration. No building or construction permit, and no Certificate of Occupancy, may issue on the property until the civil penalty is paid in full. The City can also impose a temporary development moratorium of up to 24 months on the parcel, giving the Planning Department, the Historic Preservation Sub-committee, and the Historic Preservation Commission time to study mitigation measures that then become mandatory conditions of any later development permit.

Beyond these administrative remedies, the City Attorney may bring a civil action for injunctive relief to stop an ongoing violation or to force complete or partial restoration, reconstruction, or replacement of a demolished, partially demolished, or altered historic structure. Property owners planning work on a listed Historical Resource, a historic district, or an adjacent historic site should secure a Certificate of Appropriateness before starting any alteration or demolition to avoid triggering this penalty structure.