In 2000, after severe losses due to Pierce's Disease in Riverside County turned out to be caused by a non-native insect called the Glassy-winged Sharpshooter, a plan and funding were developed to assist County Agricultural Commissioners with determining whether GWSS was present in their counties, educating the public about the threat, and where not present, preventing its introduction.

The specter of the destruction of Napa County's vineyard and winery industry, an industry that contributes over $9 billion to the state's economy annually, spurred Napa's Agricultural Commissioner to seek alliances with the county's agricultural industry leaders for the purpose of establishing an inspection program for incoming nursery stock that went beyond what the California Department of Food and Agriculture could fund. The result was the creation of the Winegrape Pest and Disease Control District in March of 2002.

The District was formed by a vote of Napa County's winegrape growers under provisions made possible by Senate Bill 594 sponsored by Senator Wesley Chesbro, Senate District 02.

The Ordinance establishing the District in Napa County law:

Ordinance 1208

An ordinance of the Board of Supervisors of the County of Napa, State of California, adding new chapter 3.54 to title 3 of the Napa County Code pertaining to the levy and collection of assessments for the Napa County Winegrape Pest and Disease Control District

The Board of Supervisors of the County of Napa ordains as follows:

A new Chapter 3.54, entitled "Assessments - Napa County Winegrape Pest and Disease Control District," is added to the Napa County Code to read in full as follows:

Chapter 3.54

Assessments - Napa County Winegrape Pest and Disease Control District

3.54.010 Authority and purpose.
3.54.020 Definitions.
3.54.030 Imposition of Assessments.
3.54.040 Fees set annually - Procedure.
3.54.050 Levy, collection, disposition and enforcement
3.54.060 Exclusions.
3.54.070 Corrections, cancellations and refunds; procedures.
3.54.080 Limitation on expenditure of funds collected.