From the Economic & Workforce Development Department | City of Oakland:

As of June 3, Alameda County is requiring masking in most indoor public settings.

This Health Order directs that face coverings must be worn over the mouth and nose – regardless of vaccination status – in all indoor public settings, venues, gatherings, and workplaces, including but not limited to offices, retail stores, restaurants and bars, theaters, family entertainment centers, conference and event centers, and State and local government offices serving the public.

Exemptions. Individuals are not required to wear face coverings in the following circumstances:

While working alone in a closed office or room;
While actively eating and/or drinking;
While swimming or showering in a fitness facility;
While obtaining a medical or cosmetic service involving the head or face for which temporary removal of the face covering is necessary to perform the service.

Individuals, businesses, venue operators, hosts, and others responsible for the operation of indoor public settings must:

Require all patrons to wear face coverings for all indoor settings, regardless of their vaccination status; and
Post clearly visible and easy-to-read signage at all entry points for indoor settings to communicate the masking requirements to all patrons.
Make reasonable efforts to ensure compliance in their setting.