Prop. 218 is part of the California Constitution and extends and provides constitutional grounding to the statutory language of Prop. 62. That one applied only to general law cities and counties in California. Prop. 218 extended that language to all of them and included additional requirements. Its purpose was to put a stop to end runs around Prop. 13 where local bureaucrats could use assessments to impose new fees and charges on property owners unrelated to an actual property benefit. That's now outlawed and after seven years, Santa Clara nor any other California county and city can't impose any assessment that is not in compliance with the terms set for in Prop. 218. Such an assessment of course, needs voter approval goes without saying.
"Show me just what Mohammed brought that was new, and there you will find things only evil and inhuman, such as his command to spread by the sword the faith he preached." - Manuel II Palelologus