Oakdale Irrigation District (OID) serves as the administration of two types of improvement districts: Domestic Improvement Districts, comprising of 5 separate districts, and Agricultural Improvement Districts, comprising of 13 separate districts.

As their names suggest, Domestic Improvement Districts were primarily established to provide drinking water to properties, while Agricultural Improvement Districts were created to deliver irrigation water.

OID does not own the Improvement Districts; rather, it manages their financial operations and oversees the maintenance and repair of the infrastructure necessary to keep each system functional. 

Each Improvement District operates as an independent entity. Property owner assessments fund the ongoing operation and maintenance of their improvement district. Improvement Districts are formed, in accordance with the CA Water Code, with OID's approval upon petition from landowners who wish to share the cost of extending and maintaining irrigation or domestic drinking services to their land.

There are five Domestic Improvement Districts that are guided by a local committee of representatives who meet with OID management at least once a year. These meetings serve to review the financial reports, discuss system performance, and consider any recommendations from either the committee or OID staff. While OID provides guideance on financial matters such as rate structures and assessment levels, it is ultimately the improvement district committee that recommends which actions best serve the interests of thier respective district and helps communicate those decision to their stakeholders.