A county supervisor may beat the city's mayor to the negotiating table on the future of Six Flags California, Valencia, with its Magic Mountain theme park and companion water park, Hurricane Harbor. City officials publicly remarked last week that they would be interested in annexing Magic Mountain and pursuing some sort of partnering with the theme park's owner, but a letter from Mayor Laurene Weste is still in the works. Supervisor Michael D. Antonovich sent a letter Tuesday to Six Flags Inc.'s chief executive officer, Mark Shapiro, to request a meeting.