CA Water Code Section 8703

Notice and service required by this article shall be provided to the person or public agency believed to be responsible for the violation and the owner of the property on which the violation occurred or is threatened to occur by one of the following means:

(a)

Hand delivery.

(b)

Certified mail.

(c)

If the person or agency cannot be reached or reasonably notified pursuant to subdivision (a) or (b), by placing a copy of the notice or order on the encroachment or property.