It appears that the Nevada County Sheriff's office - and perhaps also the city police office(s) - may be asking 9-1-1 callers for personal information in order to run warrant checks on them.
If you dial 9-1-1 in Nevada County to report an emergency, you may be asked for your name, address and date of birth even when the emergency you're reporting has nothing to do with you. When you ask why, you may get some awkward answers - "to make sure you're you", "to distinguish between you and someone else of the same name in the same household", and the like.
From an informal survey, it seems this isn't usual, & that other locales generally don't require this additional personal information - information which may then become public, since the 9-1-1 recordings have been held to be public.
(is this private information redacted from the public record?)
On at least one occasion, a 9-1-1 dispatcher has refused to accept relevant details about an incident after the caller refused to provide their personal information. And it's not clear whether the officers have been dispatched before the dispatcher asks for this information, or whether "all the boxes must be filled in first".
I don't have the time to nail this story down - but if you'd like to do so, the "police department report" section of the video of the Jul 28, 2010 July Nevada City City Council meeting would be a good starting point. You'll also want to talk to the Sheriff's Department spokesman, and ask direct and pointed questions. Nevada City councilmembers may also be helpful.
Detail: I'm told the Nevada City incident reported in the meeting occurred during regular business hours on a weekday, though you may want to confirm this.