The San Mateo County Department of Agriculture/Weights & Measures is a regulatory and informational agency serving agriculture, industry and the community. The County Agricultural Commissioner/Sealer of Weights and Measures is the local enforcement authority for California Department of Food and Agriculture and California Department of Pesticide Regulation.


To protect agricultural and environmental resources, ensure the safe use of pesticides, prevent the introduction of invasive pests, provide consumer protection and ensure equity in the marketplace.


The County Agriculture Department is under the direction of the County’s Agricultural Commissioner, who is appointed under state statute and is responsible for the administration and enforcement of all applicable laws and regulations related to environmental and consumer protection.


The Agricultural Commissioner and staff are responsible for the regulation of the agricultural industry to promote sustainability and protect the health, safety, and welfare of the public and farming community. These mandates are implemented through environmental protection programs which include pest exclusion, pest detection, pest eradication, and pesticide use enforcement; consumer protection programs which include nursery and seed inspections, fruit and vegetable standardization, and shell egg quality control; and other programs such as apiary certification, fruit and vegetable certification, and agricultural statistics.

The Pest Exclusion program prevents the introduction of pests. Shipments of plant material entering the county through SFO, or common carrier such as UPS or FedEx are inspected to ensure they are free of potentially harmful pests and invasive species. Certificates required for the export of fruits, vegetables, flowers, and other agricultural commodities are issued upon a determination that the shipments meets the entry requirements of the destination state or country.

The Pest Detection program uses systematic surveys to search for and detect any introduced plant disease, insect, animal, nematode, or weed that may be detrimental to agriculture, ornamental plantings, native habitats or the environment. Insect detection traps for priority pests such as exotic fruitflies, Gypsy moth and other regulated insect pests are deployed and maintained throughout the county.

The purpose of the Pesticide Use Enforcement program is to regulate agricultural and structural pest control chemical usage to achieve acceptable levels of control with the least possible harm to non-target organisms. The program also assures the safest possible conditions to prevent impacts to the applicator, public, and the environment.

Consumer protection programs are intended to assure that nursery stock, produce, and eggs meet all regulatory standards, and are correctly labeled with identity, quantity and responsibility statements to ensure traceability in the event of a recall. Certificates attesting to the products cleanliness and compliance with regulatory compliance are issued for shipments destined to other states or countries. The Agricultural Commissioner’s Office may also be responsible for various weed control programs, animal damage control programs, or environmental health programs, and is typically involved with land use planning issues.


The County Weights and Measures Department is directed by the Sealer of Weights and Measures, who is appointed by the Board of Supervisors and is responsible for the administration and enforcement of all applicable laws and regulations related to commercial weighing and measuring devices, package quantity control, petroleum product inspections, and the regulation of point-of-sale systems (scanners). In San Mateo County, and most other counties, the Sealer of Weights and Measures is also the Agricultural Commissioner.


The Sealer of Weights and Measures is responsible for the preservation, maintenance, and enforcement of measurement standards (weight, volume, time, distance) necessary for value comparison by consumers and essential for fair competition within industry. This charge is accomplished by comparing the performance of weighing and measuring devices against certified standards, inspecting prepackaged products to verify label statements, conducting annual weighmaster audits, and the inspection of petroleum products to verify they meet the standards represented on the product label. Weighing and measuring devices which have been inspected and found in compliance are “sealed”, thereby assuring users that the device is accurate and meets state standards.

The Device Enforcement program protects both the buyer and seller by testing weighing and measuring devices to make certain they are accurate, properly installed, and type approved. This ensures accurate and uniform standards of weight and measure when the price paid for goods depends on the use of these devices. Most devices, including retail scales, gas pumps, cordage, fabric and taxi meters, are tested yearly.

The Quantity Control program ensures accurate representation of quantity standards and price extension on packages or any item or service, sold by weight, volume, time, or count. Quantity control inspection verifies that the information on product labels concerning identity, quantity, and responsibility are accurate and in compliance with regulatory standards. Quantity control inspections include verification of tare when it is used and that price calculations are correct, including items sold over a scale such as at a butcher or delicatessen.

The Weighmaster Enforcement program protects persons having a financial interest in transactions which are based upon a written statement of quantity. A state licensed weighmaster verifies, documents, and legally attests a shipment’s quantity of product thru a weighmaster certificate. Businesses that use heavy capacity scales such as rock, sand, and gravel companies, or bulk shipments of agricultural commodities such as wine grapes, rice, corn, etc., are generally weighmasters.

The Petroleum Products Enforcement program ensures that petroleum products, such as vehicle fuels, oil, hydraulic fluids meet minimum state safety and performance standards, as well as the standards represented on the product label. Petroleum samples surveys are done annually, with samples submitted to the state lab for testing of purity, octane, viscosity and other relevant characteristics.

The Registered Service Agency program registers businesses who install, service or repair commercial weighing and measuring devices. Service agents notify the county sealer whenever adjustments are made on a commercial weighing or measuring device, and the sealer then verifies the device is in compliance with state standards.

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(650) 363-4700