in 2003, the Board of Supervisors adopted a policy on the acceptance of roads into the County Maintained Road System. In general, this policy requires that new roads or extensions of existing roads have a way to fund future road maintenance. A road can be brought into the County maintained system by forming a new sub-zone or annexing into an existing sub zone to fund road maintenance. The PRD works like an assessment district where assessments to fund major road maintenance projects (such as slurry seals and asphalt overlays) are collected on the tax bill of properties included within the boundary of the PRD sub-zone. Each year the assessments are adjusted based upon a consumer price index (CPI).