Where are the Independent strongholds in California's political landscape?

CALIFORNIA TOP TWO
California's Independent strongholds and the political calculus of the top-two open primary (by Damon Eris, CAIVN) One might easily conclude that two Democrats would be assured the top two spots in the primary and head to the general election, since it is a Democratic majority district.  But, if there were a Democratic favorite supported by half of all registered Democrats, with the rest of the district's Democrats more or less equally supporting the other five Democrats in the race, the Republican, Independent or third party candidate could easily advance to the general election with as little as 8-10% support in the primary, depending on how the district's Independents vote.  It is for this precise reason that the state's Democratic and Republican parties are considering holding caucuses or conventions prior to any such primary elections, to nominate the candidate who would be the "official" representative of the party at those elections and hopefully avoid splitting their party's vote.