Low voter turnout in primary election

Hawaii's primary election this weekend sported the lowest turnout in Hawaii primary history (to be clear, this was not a presidential primary) - that's 36.9% turnout.  Primaries do not usually attract high turnout, but there were three mayors' offices up for grabs this weekend.  Nobody seems to be worried about the presidential election, though.  Voter registration surged earlier this year in Hawaii and there has only been speculation that Hawaii's four electoral votes will be a valuable commodity despite their small number.