Hi and welcome to Just Answer! I'm happy to help with your tax questions. Feel free to interject at any time if you need clarification.
There would be no sales tax liability on the membership dues you describe. In California, membership fees are only taxable for sales tax purposes, if the fees are required in order to purchase taxable items.
Additionally, the fees would be considered nominal in amount at only $30 a year. California consider dues under $55 to be nominal in amount.