The Santa Clara County Hazardous Materials Storage Ordinance (HMSO) is an essential part of keeping our community safe. Its purpose is to protect human and environmental health through prevention and control of unauthorized discharges of hazardous materials.
Santa Clara County Code of Ordinances, Title B, Division B11, Chapter XIII
The HMSO applies to any facility, which stores hazardous materials, in the cities of Los Altos Hills, Monte Sereno, and Saratoga, as well as all unincorporated areas of Santa Clara County (including Moffett Field, San Martin, and Stanford).
- You must disclose your hazardous materials. This may be done by electronically submitting a Hazardous Materials Business Plan. If you do not have HMBP-threshold materials, a Hazardous Materials Registration Form may be submitted instead. Please see our electronic reporting page for more details.
- On CERS, the Registration Form consists of two submittal elements: Facility Information and Hazardous Materials Inventory. At this time, we are only accepting submittals through FrontCounter for Hazardous Materials Business Plan facilities. If your facility is not an HMBP facility (e.g., you are only subject to HMSO), please use CERS.
- Monitor hazardous materials storage areas in accordance with an approved monitoring plan.
- Provide secondary containment for all hazardous materials.
- Separate incompatible materials.
- Post emergency response procedures.
- Pay an annual invoice to keep your permit active.
Forms & Documents
If your facility is subject to the Hazardous Materials Business Plan program, permit fees are based upon the number of HMBP-reportable materials you have. If your facility is not subject to the HMBP program, view your fees here.
Frequently Asked Questions
Please view FAQs here.