After 20 years, the Delta County Historical Society is changing its membership format. Annual membership has been $7.50 for seniors and $10 for non-seniors. Beginning this year, the annual membership for all adults, senior and non-senior, single or couple, will be combined to one flat fee of $15. Three additional levels of membership were established to define donation levels. Four levels of membership are available -- bronze, $15 to $49 (annually); silver, $50 to $249 (annually); gold, $250 to $499 (accrued); and platinum, $500+ (accrued). Membership benefits are the same at all four levels. Members have free access to the museum and will receive a quarterly newsletter. For more information, call the museum at 874-8721 or stop by 251 Meeker Street, Delta.