Robin, not to be a sceptic: I have recently moved to hawaii though spent the last 5 years in the califonia working for a large engineering firm. It is difficult to get buy in from the engineers as the systems are simply not as functional there as they are in the NW. The reason for this is that the NW has rain year round whereas cali has no rain for most of the year then very large storms. As such, these systems often (not always) require supplemental irrigation to remain green all year. Moreover, in order to hold back a typical storm, they must be quite large.
Not looking to hold you back, just provide thier perspective. Good luck!