Here’s a statement that won’t earn me a PhD in political science: Voter turnout will determine many races in Tuesday’s primary. We all know that truth, what we don’t know is what the turnout might be.

My prediction—low, perhaps very, very low — less than one-third of California’s 17-million registered voters.

The Secretary of State does not predict voter turnout and the SOS website specifically “discourages voters from focusing on such predictions.” However, we can take some clues from recent June primary elections.

Voter turnout for primary elections since 1980 has ranged from 28.2 percent to 63.3 percent of registered voters.

That may be the range but the top percentage occurred way back in 1980. The low number of 28.2% was more recent—2008. In fact, the last few June primary election turnouts have been the lowest in over thirty years, with only a 33.6% turnout in 2006 and 33.3% in June 2010.

Voter turnout can certainly determine how elections are decided. In yesterday’s Field Poll release, the poll noted that voters age 65 or older would comprise one-third of the primary vote, a demographic that opposes the Proposition 29 cigarette tax, for example, while younger age groups that support the measure in the poll are not expected to turn out in strong numbers. That could be a determining factor in the final result.

June primaries usually bring out more conservative and older voters in greater percentages unless there is a compelling ballot measure or race for office that draws attention. That is not the case this year.

There is no overwhelming passion for an initiative and no presidential races to speak of (sorry Fred Karger).

Tony Quinn, co-editor of the California Target Book, that closely monitors California elections, wrote in a recent Target Book Hot Sheet, “The best election for comparison purposes is the legislative primary in June 2008.  June 2010 is not a good comparison because of heated primaries for state offices; there is none of that this year, and the presidential contest will not bring out additional voters, as it is decided in both parties.  There are no ballot measures that by themselves will bring out voters.”

According to Quinn, as of May 30, 2012, the counties have reported that 1,352,000 ballots have already been cast.  In 2008, there were 2,671,000 vote-by-mail ballots, so a number equal to half the vote by mail ballots in 2008 has been cast less than a week prior to voting day.

Recently, California elections are edging toward half the votes cast come from absentee ballots. Unless there is a landslide of absentee ballots this week, the absentee vote total will probably be behind 2008 levels.

All signs indicate a low turnout.

I won’t be too far out on a limb to predict that voter turnout for this primary election will be around, very possibly under, 30%.