Is it possible to filter the Calendar View via script?

Users in the application I'm building belong to various company sites in different physical locations. I'm trying to find a way of displaying the Calendar View, filtered by the user's location, without the user manually selecting this filter. In addition, it is important that Site A cannot access Site B's calendar.

Currently all the Tasks go into one Calendar View. I don't think it is an option to create additional Calendar Views for each site as this would neccesitate individual Add Task forms.

This is a "show stopper" at the moment so any help greatly appreciated!